The forces of attraction which hold an individual molecule together (for example, the covalent bonds) are known as
intramolecular attractions. All molecules experience intermolecular attractions, although in some cases those attractions are very weak. Even in a gas like hydrogen, H2, if you slow the molecules down by cooling the gas, the attractions are large enough for the molecules to stick together eventually to form a liquid and then a solid. In hydrogen's case the attractions are so weak that the molecules have to be cooled to (-252°C) before the attractions are enough to condense the hydrogen as a liquid. Helium's intermolecular attractions are even weaker - the molecules won't stick together to form a liquid until the temperature drops to (-269°C). HYDROGEN BONDING Polar molecules, such as water molecules, have a weak, partial negative charge at one region of the molecule (the oxygen atom in water) and a partial positive charge elsewhere (the hydrogen atoms in water). Thus when water molecules are close together, their positive and negative regions are attracted to the oppositely-charged regions of nearby molecules. The force of attraction, shown here as a dotted line, is called a hydrogen bond. Each water molecule is hydrogen bonded to four others. The hydrogen bonds that form between water molecules account for some of the essential — and unique — properties of water.  The attraction created by hydrogen bonds keeps water liquid over a wider range of temperature than is found for any other molecule its size.  The energy required to break multiple hydrogen bonds causes water to have a high heat of vaporization; that is; a large amount of energy is needed to convert liquid water, where the molecules are attracted through their hydrogen bonds, to water vapor, where they are not. Liquid Water and Hydrogen Bonding Why water is a liquid? In many ways, water is a miracle liquid. Since the hydrogen and oxygen atoms in the molecule carry opposite (though partial) charges, nearby water molecules are attracted to each other like tiny little magnets. Hydrogen bonding makes water molecules "stick" together. This makes water have high melting and boiling points compared to other covalent compounds such as ammonia (NH3) which have similar molecular mass but are gases Ice and Hydrogen Bonding The structure that forms in the solid ice crystal actually has large holes in it. Therefore, in a given volume of ice, there are fewer water molecules than in the same volume of liquid water.


Hydrogen bonding makes water molecules "stick" together. This makes water have high melting and boiling points compared to other covalent compounds such as ammonia (NH3) which have similar molecular mass but are gases Ice and Hydrogen Bonding The structure that forms in the solid ice crystal actually has large holes in it. Therefore, in a given volume of ice, there are fewer water molecules than in the same volume of liquid water. In other words, ice is less dense than liquid water and will float on the surface of the liquid. Surface Tension and hydrogen bonding As we just discussed, neighboring water molecules are attracted to one another. Molecules at the surface of liquid water have fewer neighbors and, as a result, have a greater attraction to the few water molecules that are nearby. This enhanced attraction is called surface tension. It makes the surface of the liquid slightly more difficult to break through than the interior. Water as a Solvent The partial charge that develops across the water molecule helps make it an excellent solvent. Water dissolves many substances by surrounding charged particles and "pulling" them into solution. For example, common table salt, sodium chloride, is an ionic substance that contains alternating sodium and chlorine ions. When table salt is added to water, the partial charges on the water molecule are attracted to the Na+ and Cl- ions. Why does ethanol have a higher boiling point than methoxymethane? Ethanol, CH3CH2-O-H, and methoxymethane, CH3-O-CH3, both have the same molecular formula, C2H6O. They have the same number of electrons, and a similar length to the molecule. The van der Waals attractions (both dispersion forces and dipole-dipole attractions) in each will be much the same. However, ethanol has a hydrogen atom attached directly to oxygen - and that oxygen still has exactly the same two lone pairs as in a water molecule. Hydrogen bonding can occur between ethanol molecules, although not as effectively as in water. The hydrogen bonding is limited by the fact that there is only one hydrogen in each ethanol molecule with sufficient + charge. In methoxymethane, the lone pairs on the oxygen are still there, but the hydrogens aren't sufficiently + for hydrogen bonds to form. Except in some rather unusual cases, the hydrogen atom has to be attached directly to the very electronegative element for hydrogen bonding to occur.


The hydrogen bonding is limited by the fact that there is only one hydrogen in each ethanol molecule with sufficient + charge. In methoxymethane, the lone pairs on the oxygen are still there, but the hydrogens aren't sufficiently + for hydrogen bonds to form. Except in some rather unusual cases, the hydrogen atom has to be attached directly to the very electronegative element for hydrogen bonding to occur. The boiling points of ethanol and methoxymethane show the dramatic effect that the hydrogen bonding has on the stickiness of the ethanol molecules:
ethanol (with hydrogen bonding) 78.5°C methoxymethane (without hydrogen bonding) -24.8°C The hydrogen bonding in the ethanol has lifted its boiling point about 100°C.It is important to realise that hydrogen bonding exists in addition to van der Waals attractions. For example, all the following molecules contain the same number of electrons, and the first two are much the same length. The higher boiling point of the butan-1-ol is due to the additional hydrogen bonding. 4. BONDING IN METALS Bonding in metals Metal atoms have relatively few electrons in their outer shells. When they are packed together, each metal atom loses its outer electrons into a ಫseaಬ of free electrons (or mobile electrons). Having lost electrons, the atoms are no longer electrically neutral. They become positive ions because they have lost electrons but the number of protons in the nucleus has remained unchanged. Therefore the structure of a metal is made up of positive ions packed together. These ions are surrounded by electrons, which can move freely between the ions.  An ion is a charged particle made from an atom by the loss or gain of electrons.  Metal atoms most easily lose electrons, so they become positive ions. In doing so they achieve a more stable electron arrangement, usually that of the nearest noble gas. These free electrons are delocalized (not restricted to orbiting one positive ion) and form a kind of electrostatic ಫglueಬ holding the structure together. In an electrical circuit, metals can conduct electricity because the mobile electrons can move through the structure carrying charge. His type of bonding (called metallic boding) is present in alloys as well. Alloys, for example solder and brass, will conduct electricity. The physical properties of metals: This strong bonding generally results in dense, strong materials with high melting and boiling points.


His type of bonding (called metallic boding) is present in alloys as well. Alloys, for example solder and brass, will conduct electricity. The physical properties of metals: This strong bonding generally results in dense, strong materials with high melting and boiling points. Usually a relatively large amount of energy is needed to melt or boil metals. a. Metals are good conductors of electricity because these 'free' electrons carry the charge of an electric current when a potential difference (voltage!) is applied across a piece of metal. b. Metals are also good conductors of heat. This is also due to the free moving electrons. Nonmetallic solids conduct heat energy by hotter more strongly vibrating atoms, knocking against cooler less strongly vibrating atoms to pass the particle kinetic energy on. In metals, as well as this effect, the 'hot' high kinetic energy electrons move around freely to transfer the particle kinetic energy more efficiently to 'cooler' atoms. c. Typical metals also have a silvery surface but remember this may be easily tarnished by corrosive oxidation in air and water. d. Unlike ionic solids, metals are very malleable, they can be readily bent, pressed or hammered into shape. INTRODUCTION TO SALTS 1.(a) A salt is an ionic compound formed when the cation from a base combine with the anion derived from an acid. A salt is therefore formed when the hydrogen ions in an acid are replaced wholly/fully or partially/partly ,directly or indirectly by a metal or ammonium radical. (b) The number of ionizable/replaceable hydrogen in an acid is called basicity of an acid. Some acids are therefore: (i)monobasic acids generally denoted HX e.g. HCl, HNO3,HCOOH,CH3COOH. (ii)dibasic acids ; generally denoted H2X e.g. H2SO4, H2SO3, H2CO3,HOOCOOH. (iii)tribasic acids ; generally denoted H3X e.g. H3PO4. (c) Some salts are normal salts while other are acid salts. (i)A normal salt is formed when all the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. (ii)An acid salt is formed when part/portion the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical.


(c) Some salts are normal salts while other are acid salts. (i)A normal salt is formed when all the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. (ii)An acid salt is formed when part/portion the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-)
Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) acid H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts.


(i)A normal salt is formed when all the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. (ii)An acid salt is formed when part/portion the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-)
Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) acid H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts. Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI)
Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence.


(ii)An acid salt is formed when part/portion the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-)
Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) acid H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts. Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI)
Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence. (i) Hygroscopic salts /compounds are those that absorb water from the atmosphere but do not form a solution.


Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-)
Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) acid H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts. Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI)
Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence. (i) Hygroscopic salts /compounds are those that absorb water from the atmosphere but do not form a solution. Some salts which are hygroscopic include anhydrous copper(II)sulphate(VI), anhydrous cobalt(II)chloride, potassium nitrate(V) common table salt.


Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI)
Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence. (i) Hygroscopic salts /compounds are those that absorb water from the atmosphere but do not form a solution. Some salts which are hygroscopic include anhydrous copper(II)sulphate(VI), anhydrous cobalt(II)chloride, potassium nitrate(V) common table salt. (ii)Deliquescent salts /compounds are those that absorb water from the atmosphere and form a solution. Some salts which are deliquescent include: Sodium nitrate(V),Calcium chloride, Sodium hydroxide, Iron(II)chloride, Magnesium chloride. (iii)Efflorescent salts/compounds are those that lose their water of crystallization to the atmosphere.


(ii)Deliquescent salts /compounds are those that absorb water from the atmosphere and form a solution. Some salts which are deliquescent include: Sodium nitrate(V),Calcium chloride, Sodium hydroxide, Iron(II)chloride, Magnesium chloride. (iii)Efflorescent salts/compounds are those that lose their water of crystallization to the atmosphere. Some salts which effloresces include: sodium carbonate decahydrate, Iron(II)sulphate(VI)heptahydrate, sodium sulphate (VI)decahydrate. (e)Some salts contain water of crystallization.They are hydrated.Others do not contain water of crystallization. They are anhydrous. Table showing some hydrated salts. Name of hydrated salt Chemical formula Copper(II)sulphate(VI)pentahydrate CuSO4.5H2O Aluminium(III)sulphate(VI)hexahydrate Al2 (SO4) 3.6H2O Zinc(II)sulphate(VI)heptahydrate ZnSO4.7H2O Iron(II)sulphate(VI)heptahydrate FeSO4.7H2O Calcium(II)sulphate(VI)heptahydrate CaSO4.7H2O Magnesium(II)sulphate(VI)heptahydrate MgSO4.7H2O Sodium sulphate(VI)decahydrate Na2SO4.10H2O Sodium carbonate(IV)decahydrate Na2CO3.10H2O Potassium carbonate(IV)decahydrate K2CO3.10H2O Potassium sulphate(VI)decahydrate K2SO4.10H2O (f)Some salts exist as a simple salt while some as complex salts. Below are some complex salts.


Table showing some hydrated salts. Name of hydrated salt Chemical formula Copper(II)sulphate(VI)pentahydrate CuSO4.5H2O Aluminium(III)sulphate(VI)hexahydrate Al2 (SO4) 3.6H2O Zinc(II)sulphate(VI)heptahydrate ZnSO4.7H2O Iron(II)sulphate(VI)heptahydrate FeSO4.7H2O Calcium(II)sulphate(VI)heptahydrate CaSO4.7H2O Magnesium(II)sulphate(VI)heptahydrate MgSO4.7H2O Sodium sulphate(VI)decahydrate Na2SO4.10H2O Sodium carbonate(IV)decahydrate Na2CO3.10H2O Potassium carbonate(IV)decahydrate K2CO3.10H2O Potassium sulphate(VI)decahydrate K2SO4.10H2O (f)Some salts exist as a simple salt while some as complex salts. Below are some complex salts. Table of some complex salts Name of complex salt Chemical formula Colour of the complex salt Tetraamminecopper(II)sulphate(VI) Cu(NH3) 4 SO4 H2O Royal/deep blue solution
Tetraamminezinc(II)nitrate(V) Zn(NH3) 4 (NO3 )2 Colourless solution Tetraamminecopper(II) nitrate(V) Cu(NH3) 4 (NO3 )2 Royal/deep blue solution Tetraamminezinc(II)sulphate(VI) Zn(NH3) 4 SO4 Colourless solution (g)Some salts exist as two salts in one. They are called double salts.


Below are some complex salts. Table of some complex salts Name of complex salt Chemical formula Colour of the complex salt Tetraamminecopper(II)sulphate(VI) Cu(NH3) 4 SO4 H2O Royal/deep blue solution
Tetraamminezinc(II)nitrate(V) Zn(NH3) 4 (NO3 )2 Colourless solution Tetraamminecopper(II) nitrate(V) Cu(NH3) 4 (NO3 )2 Royal/deep blue solution Tetraamminezinc(II)sulphate(VI) Zn(NH3) 4 SO4 Colourless solution (g)Some salts exist as two salts in one. They are called double salts. Table of some double salts Name of double salts Chemical formula Trona(sodium sesquicarbonate) Na2CO3 NaHCO3.2H2O Ammonium iron(II)sulphate(VI) FeSO4(NH4) 2SO4.2H2O Ammonium aluminium(III)sulphate(VI) Al2(SO4) 3(NH4) 2SO4.H2O (h)Some salts dissolve in water to form a solution. They are said to be soluble. Others do not dissolve in water. They form a suspension/precipitate in water.


They are said to be soluble. Others do not dissolve in water. They form a suspension/precipitate in water. Table of solubility of salts Soluble salts Insoluble salts All nitrate(V)salts All sulphate(VI)/SO42- salts except Barium(II) sulphate(VI)/BaSO4 Calcium(II) sulphate(VI)/CaSO4 Lead(II) sulphate(VI)/PbSO4 All sulphate(IV)/SO32- salts except Barium(II) sulphate(IV)/BaSO3 Calcium(II) sulphate(IV)/CaSO3 Lead(II) sulphate(IV)/PbSO3 All chlorides/Cl- except Silver chloride/AgCl Lead(II)chloride/PbCl2(dissolves in hot water) All phosphate(V)/PO43- All sodium,potassium and ammonium salts All hydrogen carbonates/HCO3- All hydrogen sulphate(VI)/ HSO4- Sodium carbonate/Na2CO3, potassium carbonate/ K2CO3, ammonium carbonate (NH4) 2CO3 except All carbonates All alkalis(KOH,NaOH, NH4OH) except All bases 13 Salts can be prepared in a school laboratory by a method that uses its solubility in water. (a) Soluble salts may be prepared by using any of the following methods: (i)Direct displacement/reaction of a metal with an acid. By reacting a metal higher in the reactivity series than hydrogen with a dilute acid,a salt is formed and hydrogen gas is evolved. Excess of the metal must be used to ensure all the acid has reacted. When effervescence/bubbling /fizzing has stopped ,excess metal is filtered. The filtrate is heated to concentrate then allowed to crystallize. Washing with distilled water then drying between filter papers produces a sample crystal of the salt. i.e.


The filtrate is heated to concentrate then allowed to crystallize. Washing with distilled water then drying between filter papers produces a sample crystal of the salt. i.e. M(s) + H2X -> MX(aq) + H2(g) Examples Mg(s) + H2SO4(aq) -> MgSO4 (aq) + H2(g) Zn(s) + H2SO4(aq) -> ZnSO4 (aq) + H2(g) Pb(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2(g) Ca(s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2(g) Mg(s) + 2HNO3(aq) -> Mg(NO3) 2(aq) + H2(g) Mg(s) + 2HCl(aq) -> MgCl 2(aq) + H2(g) Zn(s) + 2HCl(aq) -> ZnCl 2(aq) + H2(g) (ii)Reaction of an insoluble base with an acid By adding an insoluble base (oxide/hydroxide )to a dilute acid until no more dissolves, in the acid,a salt and water are formed. Excess of the base is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter papers e.g.


M(s) + H2X -> MX(aq) + H2(g) Examples Mg(s) + H2SO4(aq) -> MgSO4 (aq) + H2(g) Zn(s) + H2SO4(aq) -> ZnSO4 (aq) + H2(g) Pb(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2(g) Ca(s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2(g) Mg(s) + 2HNO3(aq) -> Mg(NO3) 2(aq) + H2(g) Mg(s) + 2HCl(aq) -> MgCl 2(aq) + H2(g) Zn(s) + 2HCl(aq) -> ZnCl 2(aq) + H2(g) (ii)Reaction of an insoluble base with an acid By adding an insoluble base (oxide/hydroxide )to a dilute acid until no more dissolves, in the acid,a salt and water are formed. Excess of the base is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter papers e.g. PbO(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2O (l) Pb(OH)2(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + 2H2O (l) CaO (s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2O (l) MgO (s) + 2HNO3(aq) -> Mg(NO3) 2(aq) + H2O (l) MgO (s) + 2HCl(aq) -> MgCl 2(aq) + H2O (l) ZnO (s) + 2HCl(aq) -> ZnCl 2(aq) + H2O (l) Zn(OH)2(s) + 2HNO3(aq) -> Zn(NO3) 2(aq) + 2H2O (l) CuO (s) + 2HCl(aq) -> CuCl 2(aq) + H2O (l) CuO (s) + H2SO4(aq) -> CuSO4(aq) + H2O (l) Ag2O(s) + 2HNO3(aq) -> 2AgNO3(aq) + H2O (l) Na2O(s) + 2HNO3(aq) -> 2NaNO3(aq) + H2O (l) (iii)reaction of insoluble /soluble carbonate /hydrogen carbonate with an acid.


Excess of the base is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter papers e.g. PbO(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2O (l) Pb(OH)2(s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + 2H2O (l) CaO (s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2O (l) MgO (s) + 2HNO3(aq) -> Mg(NO3) 2(aq) + H2O (l) MgO (s) + 2HCl(aq) -> MgCl 2(aq) + H2O (l) ZnO (s) + 2HCl(aq) -> ZnCl 2(aq) + H2O (l) Zn(OH)2(s) + 2HNO3(aq) -> Zn(NO3) 2(aq) + 2H2O (l) CuO (s) + 2HCl(aq) -> CuCl 2(aq) + H2O (l) CuO (s) + H2SO4(aq) -> CuSO4(aq) + H2O (l) Ag2O(s) + 2HNO3(aq) -> 2AgNO3(aq) + H2O (l) Na2O(s) + 2HNO3(aq) -> 2NaNO3(aq) + H2O (l) (iii)reaction of insoluble /soluble carbonate /hydrogen carbonate with an acid. By adding an excess of a soluble /insoluble carbonate or hydrogen carbonate to adilute acid, effervescence /fizzing/bubbling out of carbon(IV)oxide gas shows the
reaction is taking place. When effervescence /fizzing/bubbling out of the gas is over, excess of the insoluble carbonate is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter paper papers e.g.


By adding an excess of a soluble /insoluble carbonate or hydrogen carbonate to adilute acid, effervescence /fizzing/bubbling out of carbon(IV)oxide gas shows the
reaction is taking place. When effervescence /fizzing/bubbling out of the gas is over, excess of the insoluble carbonate is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter paper papers e.g. PbCO3 (s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2O (l)+ CO2(g) ZnCO3 (s) + 2HNO3(aq) -> Zn(NO3) 2(aq) + H2O (l)+ CO2(g) CaCO3 (s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2O (l)+ CO2(g) MgCO3 (s) + H2SO4(aq) -> MgSO4(aq) + H2O (l)+ CO2(g) Cu CO3 (s) + H2SO4(aq) -> CuSO4(aq) + H2O (l) + CO2(g) Ag2CO3 (s) + 2HNO3(aq) -> 2AgNO3(aq) + H2O (l) + CO2(g) Na2CO3 (s) + 2HNO3(aq) -> 2NaNO3(aq) + H2O (l) + CO2(g) K2CO3 (s) + 2HCl(aq) -> 2KCl(aq) + H2O (l) + CO2(g) NaHCO3 (s) + HNO3(aq) -> NaNO3(aq) + H2O (l) + CO2(g) KHCO3 (s) + HCl(aq) -> KCl(aq) + H2O (l) + CO2(g) (iv)neutralization/reaction of soluble base/alkali with dilute acid By adding an acid to a burette into a known volume of an alkali with 2-3 drops of an indicator, the colour of the indicator changes when the acid has completely reacted with an alkali at the end point.


When effervescence /fizzing/bubbling out of the gas is over, excess of the insoluble carbonate is filtered off. The filtrate is heated to concentrate ,allowed to crystallize then washed with distilled water before drying between filter paper papers e.g. PbCO3 (s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2O (l)+ CO2(g) ZnCO3 (s) + 2HNO3(aq) -> Zn(NO3) 2(aq) + H2O (l)+ CO2(g) CaCO3 (s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2O (l)+ CO2(g) MgCO3 (s) + H2SO4(aq) -> MgSO4(aq) + H2O (l)+ CO2(g) Cu CO3 (s) + H2SO4(aq) -> CuSO4(aq) + H2O (l) + CO2(g) Ag2CO3 (s) + 2HNO3(aq) -> 2AgNO3(aq) + H2O (l) + CO2(g) Na2CO3 (s) + 2HNO3(aq) -> 2NaNO3(aq) + H2O (l) + CO2(g) K2CO3 (s) + 2HCl(aq) -> 2KCl(aq) + H2O (l) + CO2(g) NaHCO3 (s) + HNO3(aq) -> NaNO3(aq) + H2O (l) + CO2(g) KHCO3 (s) + HCl(aq) -> KCl(aq) + H2O (l) + CO2(g) (iv)neutralization/reaction of soluble base/alkali with dilute acid By adding an acid to a burette into a known volume of an alkali with 2-3 drops of an indicator, the colour of the indicator changes when the acid has completely reacted with an alkali at the end point. The procedure is then repeated without the indicator .The solution mixture is then heated to concentrate , allowed to crystallize ,washed with distilled water before drying with filter papers. e.g.


PbCO3 (s) + 2HNO3(aq) -> Pb(NO3) 2(aq) + H2O (l)+ CO2(g) ZnCO3 (s) + 2HNO3(aq) -> Zn(NO3) 2(aq) + H2O (l)+ CO2(g) CaCO3 (s) + 2HNO3(aq) -> Ca(NO3) 2(aq) + H2O (l)+ CO2(g) MgCO3 (s) + H2SO4(aq) -> MgSO4(aq) + H2O (l)+ CO2(g) Cu CO3 (s) + H2SO4(aq) -> CuSO4(aq) + H2O (l) + CO2(g) Ag2CO3 (s) + 2HNO3(aq) -> 2AgNO3(aq) + H2O (l) + CO2(g) Na2CO3 (s) + 2HNO3(aq) -> 2NaNO3(aq) + H2O (l) + CO2(g) K2CO3 (s) + 2HCl(aq) -> 2KCl(aq) + H2O (l) + CO2(g) NaHCO3 (s) + HNO3(aq) -> NaNO3(aq) + H2O (l) + CO2(g) KHCO3 (s) + HCl(aq) -> KCl(aq) + H2O (l) + CO2(g) (iv)neutralization/reaction of soluble base/alkali with dilute acid By adding an acid to a burette into a known volume of an alkali with 2-3 drops of an indicator, the colour of the indicator changes when the acid has completely reacted with an alkali at the end point. The procedure is then repeated without the indicator .The solution mixture is then heated to concentrate , allowed to crystallize ,washed with distilled water before drying with filter papers. e.g. NaOH (aq) + HNO3(aq) -> NaNO3(aq) + H2O (l) KOH (aq) + HNO3(aq) -> KNO3(aq) + H2O (l) KOH (aq) + HCl(aq) -> KCl(aq) + H2O (l) 2KOH (aq) + H2SO4(aq) -> K2SO4(aq) + 2H2O (l) 2 NH4OH (aq) + H2SO4(aq) -> (NH4)2SO4(aq) + 2H2O (l) NH4OH (aq) + HNO3(aq) -> NH4NO3(aq) + H2O (l) (iv)direct synthesis/combination.


The procedure is then repeated without the indicator .The solution mixture is then heated to concentrate , allowed to crystallize ,washed with distilled water before drying with filter papers. e.g. NaOH (aq) + HNO3(aq) -> NaNO3(aq) + H2O (l) KOH (aq) + HNO3(aq) -> KNO3(aq) + H2O (l) KOH (aq) + HCl(aq) -> KCl(aq) + H2O (l) 2KOH (aq) + H2SO4(aq) -> K2SO4(aq) + 2H2O (l) 2 NH4OH (aq) + H2SO4(aq) -> (NH4)2SO4(aq) + 2H2O (l) NH4OH (aq) + HNO3(aq) -> NH4NO3(aq) + H2O (l) (iv)direct synthesis/combination. When a metal burn in a gas jar containing a non metal , the two directly combine to form a salt. e.g. 2Na(s) + Cl2(g) -> 2NaCl(s) 2K(s) + Cl2(g) -> 2KCl(s) Mg(s) + Cl2(g) -> Mg Cl2 (s) Ca(s) + Cl2(g) -> Ca Cl2 (s) Some salts once formed undergo sublimation and hydrolysis. Care should be taken to avoid water/moisture into the reaction flask during their preparation.Such salts include aluminium(III)chloride(AlCl3) and iron (III)chloride(FeCl3)
1. Heated aluminium foil reacts with chlorine to form aluminium(III)chloride that sublimes away from the source of heating then deposited as solid again 2Al(s) + 3Cl2(g) -> 2AlCl3 (s/g) Once formed aluminium(III)chloride hydrolyses/reacts with water vapour / moisture present to form aluminium hydroxide solution and highly acidic fumes of hydrogen chloride gas. AlCl3(s)+ 3H2 O(g) -> Al(OH)3 (aq) + 3HCl(g) 2.


Care should be taken to avoid water/moisture into the reaction flask during their preparation.Such salts include aluminium(III)chloride(AlCl3) and iron (III)chloride(FeCl3)
1. Heated aluminium foil reacts with chlorine to form aluminium(III)chloride that sublimes away from the source of heating then deposited as solid again 2Al(s) + 3Cl2(g) -> 2AlCl3 (s/g) Once formed aluminium(III)chloride hydrolyses/reacts with water vapour / moisture present to form aluminium hydroxide solution and highly acidic fumes of hydrogen chloride gas. AlCl3(s)+ 3H2 O(g) -> Al(OH)3 (aq) + 3HCl(g) 2. Heated iron filings reacts with chlorine to form iron(III)chloride that sublimes away from the source of heating then deposited as solid again 2Fe(s) + 3Cl2(g) -> 2FeCl3 (s/g) Once formed , aluminium(III)chloride hydrolyses/reacts with water vapour / moisture present to form aluminium hydroxide solution and highly acidic fumes of hydrogen chloride gas. FeCl3(s)+ 3H2 O(g) -> Fe(OH)3 (aq) + 3HCl(g) (b)Insoluble salts can be prepared by reacting two suitable soluble salts to form one soluble and one insoluble. This is called double decomposition or precipitation. The mixture is filtered and the residue is washed with distilled water then dried.


FeCl3(s)+ 3H2 O(g) -> Fe(OH)3 (aq) + 3HCl(g) (b)Insoluble salts can be prepared by reacting two suitable soluble salts to form one soluble and one insoluble. This is called double decomposition or precipitation. The mixture is filtered and the residue is washed with distilled water then dried. CuSO4(aq) + Na2CO3 (aq) -> CuCO3 (s) + Na2 SO4(aq) BaCl2(aq) + K2SO4 (aq) -> BaSO4 (s) + 2KCl (aq) Pb(NO3)2(aq) + K2SO4 (aq) -> PbSO4 (s) + 2KNO3 (aq) 2AgNO3(aq) + MgCl2 (aq) -> 2AgCl(s) + Mg(NO3)2 (aq) Pb(NO3)2(aq) + (NH4) 2SO4 (aq) -> PbSO4 (s) + 2NH4NO 3(aq) BaCl2(aq) + K2SO3 (aq) -> BaSO3 (s) + 2KCl (aq) 14. Salts may lose their water of crystallization , decompose ,melt or sublime on heating on a Bunsen burner flame. The following shows the behavior of some salts on heating gently /or strongly in a laboratory school burner: (a)effect of heat on chlorides All chlorides have very high melting and boiling points and therefore are not affected by laboratory heating except ammonium chloride. Ammonium chloride sublimes on gentle heating. It dissociate into the constituent ammonia and hydrogen chloride gases on strong heating. NH4Cl(s) NH4Cl(g) NH3(g) + HCl(g) (sublimation) (dissociation) (b)effect of heat on nitrate(V) (i) Potassium nitrate(V)/KNO3 and sodium nitrate(V)/NaNO3 decompose on heating to form Potassium nitrate(III)/KNO2 and sodium nitrate(III)/NaNO2 and producing Oxygen gas in each case.


Ammonium chloride sublimes on gentle heating. It dissociate into the constituent ammonia and hydrogen chloride gases on strong heating. NH4Cl(s) NH4Cl(g) NH3(g) + HCl(g) (sublimation) (dissociation) (b)effect of heat on nitrate(V) (i) Potassium nitrate(V)/KNO3 and sodium nitrate(V)/NaNO3 decompose on heating to form Potassium nitrate(III)/KNO2 and sodium nitrate(III)/NaNO2 and producing Oxygen gas in each case. 2KNO3 (s) -> 2KNO2(s) + O2(g) 2NaNO3 (s) -> 2NaNO2(s) + O2(g) (ii)Heavy metal nitrates(V) salts decompose on heating to form the oxide and a mixture of brown acidic nitrogen(IV)oxide and oxygen gases. e.g. 2Ca(NO3)2 (s) -> 2CaO(s) + 4NO2(g) + O2(g) 2Mg(NO3)2(s) -> 2MgO(s) + 4NO2(g) + O2(g) 2Zn(NO3)2(s) -> 2ZnO(s) + 4NO2(g) + O2(g) 2Pb(NO3)2(s) -> 2PbO(s) + 4NO2(g) + O2(g) 2Cu(NO3)2(s) -> 2CuO(s) + 4NO2(g) + O2(g) 2Fe(NO3)2(s) -> 2FeO(s) + 4NO2(g) + O2(g) (iii)Silver(I)nitrate(V) and mercury(II) nitrate(V) are lowest in the reactivity series. They decompose on heating to form the metal(silver and mercury)and the Nitrogen(IV)oxide and oxygen gas. i.e.


2Ca(NO3)2 (s) -> 2CaO(s) + 4NO2(g) + O2(g) 2Mg(NO3)2(s) -> 2MgO(s) + 4NO2(g) + O2(g) 2Zn(NO3)2(s) -> 2ZnO(s) + 4NO2(g) + O2(g) 2Pb(NO3)2(s) -> 2PbO(s) + 4NO2(g) + O2(g) 2Cu(NO3)2(s) -> 2CuO(s) + 4NO2(g) + O2(g) 2Fe(NO3)2(s) -> 2FeO(s) + 4NO2(g) + O2(g) (iii)Silver(I)nitrate(V) and mercury(II) nitrate(V) are lowest in the reactivity series. They decompose on heating to form the metal(silver and mercury)and the Nitrogen(IV)oxide and oxygen gas. i.e. 2AgNO3(s) -> 2Ag (s) + 2NO2(g) + O2(g) 2Hg(NO3)2 (s) -> 2Hg (s) + 4NO2(g) + O2(g) (iv)Ammonium nitrate(V) and Ammonium nitrate(III) decompose on heating to Nitrogen(I)oxide(relights/rekindles glowing splint) and nitrogen gas respectively.Water is also formed.i.e. NH4NO3(s) -> N2O (g) + H2O(l) NH4NO2(s) -> N2 (g) + H2O(l) (c) effect of heat on nitrate(V) Only Iron(II)sulphate(VI), Iron(III)sulphate(VI) and copper(II)sulphate(VI) decompose on heating. They form the oxide, and produce highly acidic fumes of acidic sulphur(IV)oxide gas.


2AgNO3(s) -> 2Ag (s) + 2NO2(g) + O2(g) 2Hg(NO3)2 (s) -> 2Hg (s) + 4NO2(g) + O2(g) (iv)Ammonium nitrate(V) and Ammonium nitrate(III) decompose on heating to Nitrogen(I)oxide(relights/rekindles glowing splint) and nitrogen gas respectively.Water is also formed.i.e. NH4NO3(s) -> N2O (g) + H2O(l) NH4NO2(s) -> N2 (g) + H2O(l) (c) effect of heat on nitrate(V) Only Iron(II)sulphate(VI), Iron(III)sulphate(VI) and copper(II)sulphate(VI) decompose on heating. They form the oxide, and produce highly acidic fumes of acidic sulphur(IV)oxide gas. 2FeSO4 (s) -> Fe2O3(s) + SO3(g) + SO2(g) Fe2(SO4) 3(s) -> Fe2O3(s) + SO3(g) CuSO4 (s) -> CuO(s) + SO3(g)
(d) effect of heat on carbonates(IV) and hydrogen carbonate(IV). (i)Sodium carbonate(IV)and potassium carbonate(IV)do not decompose on heating. (ii)Heavy metal nitrate(IV)salts decompose on heating to form the oxide and produce carbon(IV)oxide gas. Carbon (IV)oxide gas forms a white precipitate when bubbled in lime water. The white precipitate dissolves if the gas is in excess. e.g. CuCO3 (s) -> CuO(s) + CO2(g) CaCO3 (s) -> CaO(s) + CO2(g) PbCO3 (s) -> PbO(s) + CO2(g) FeCO3 (s) -> FeO(s) + CO2(g) ZnCO3 (s) -> ZnO(s) + CO2(g) (iii)Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV)decompose on heating to give the corresponding carbonate (IV) and form water and carbon(IV)oxide gas. i.e.


e.g. CuCO3 (s) -> CuO(s) + CO2(g) CaCO3 (s) -> CaO(s) + CO2(g) PbCO3 (s) -> PbO(s) + CO2(g) FeCO3 (s) -> FeO(s) + CO2(g) ZnCO3 (s) -> ZnO(s) + CO2(g) (iii)Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV)decompose on heating to give the corresponding carbonate (IV) and form water and carbon(IV)oxide gas. i.e. 2NaHCO 3(s) -> Na2CO3(s) + CO2(g) + H2O(l) 2KHCO 3(s) -> K2CO3(s) + CO2(g) + H2O(l) (iii) Calcium hydrogen carbonate (IV) and Magnesium hydrogen carbonate(IV) decompose on heating to give the corresponding carbonate (IV) and form water and carbon(IV)oxide gas. i. e. Ca(HCO3) 2(aq) -> CaCO3(s) + CO2(g) + H2O(l) Mg(HCO3) 2(aq) -> MgCO3(s) + CO2(g) + H2O(l)
1 INTRODUCTION TO ELECTROLYSIS (ELECTROLYTIC CELL) 1.Electrolysis is defined simply as the decomposition of a compound by an electric current/electricity. A compound that is decomposed by an electric current is called an electrolyte. Some electrolytes are weak while others are strong. 2.Strong electrolytes are those that are fully ionized/dissociated into (many) ions. Common strong electrolytes include: (i)all mineral acids (ii)all strong alkalis/sodium hydroxide/potassium hydroxide. (iii)all soluble salts 3.Weak electrolytes are those that are partially/partly ionized/dissociated into (few) ions. Common weak electrolytes include: (i)all organic acids (ii)all bases except sodium hydroxide/potassium hydroxide. (iii)Water 4. A compound that is not decomposed by an electric current is called nonelectrolyte.


Common weak electrolytes include: (i)all organic acids (ii)all bases except sodium hydroxide/potassium hydroxide. (iii)Water 4. A compound that is not decomposed by an electric current is called nonelectrolyte. Non-electrolytes are those compounds /substances that exist as molecules and thus cannot ionize/dissociate into(any) ions . Common non-electrolytes include: (i) most organic solvents (e.g. petrol/paraffin/benzene/methylbenzene/ethanol) (ii)all hydrocarbons(alkanes /alkenes/alkynes) (iii)Chemicals of life(e.g. proteins, carbohydrates, lipids, starch, sugar) 5. An electrolytes in solid state have fused /joined ions and therefore do not conduct electricity but the ions (cations and anions) are free and mobile in molten and aqueous (solution, dissolved in water) state. 6.During electrolysis, the free ions are attracted to the electrodes. An electrode is a rod through which current enter and leave the electrolyte during electrolysis. 2 An electrode that does not influence/alter the products of electrolysis is called an inert electrode. Common inert electrodes include: (i)Platinum (ii)Carbon graphite Platinum is not usually used in a school laboratory because it is very expensive. Carbon graphite is easily/readily and cheaply available (from used dry cells). 7.The positive electrode is called Anode.The anode is the electrode through which current enter the electrolyte/electrons leave the electrolyte 8.The negative electrode is called Cathode. The cathode is the electrode through which current leave the electrolyte / electrons enter the electrolyte 9. During the electrolysis, free anions are attracted to the anode where they lose /donate electrons to form neutral atoms/molecules. i.e. M(l) -> M+(l) + e (for cations from molten electrolytes) M(s) -> M+(aq) + e (for cations from electrolytes in aqueous state / solution / dissolved in water) The neutral atoms /molecules form the products of electrolysis at the anode. This is called discharge at anode 10. During electrolysis, free cations are attracted to the cathode where they gain /accept/acquire electrons to form neutral atoms/molecules.


M(l) -> M+(l) + e (for cations from molten electrolytes) M(s) -> M+(aq) + e (for cations from electrolytes in aqueous state / solution / dissolved in water) The neutral atoms /molecules form the products of electrolysis at the anode. This is called discharge at anode 10. During electrolysis, free cations are attracted to the cathode where they gain /accept/acquire electrons to form neutral atoms/molecules. X+ (aq) + 2e -> X(s) (for cations from electrolytes in aqueous state / solution / dissolved in water) 2X+ (l) + 2e -> X (l) (for cations from molten electrolytes) The neutral atoms /molecules form the products of electrolysis at the cathode. This is called discharge at cathode. 11. The below set up shows an electrolytic cell. 3 BatteryAnode(+)Cathode(-)ElectrolyteSimple set up of electrolytic cellGaseous product at anodeGaseous product at cathode 12. For a compound /salt containing only two ion/binary salt the products of electrolysis in an electrolytic cell can be determined as in the below examples: a)To determine the products of electrolysis of molten Lead(II)chloride (i)Decomposition of electrolyte into free ions; PbCl2 (l) -> Pb 2+(l) + 2Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Pb 2+(l) + 2e -> Pb (l) (Cation / Pb 2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid lead metal. II.At the anode pale green chlorine gas.


3 BatteryAnode(+)Cathode(-)ElectrolyteSimple set up of electrolytic cellGaseous product at anodeGaseous product at cathode 12. For a compound /salt containing only two ion/binary salt the products of electrolysis in an electrolytic cell can be determined as in the below examples: a)To determine the products of electrolysis of molten Lead(II)chloride (i)Decomposition of electrolyte into free ions; PbCl2 (l) -> Pb 2+(l) + 2Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Pb 2+(l) + 2e -> Pb (l) (Cation / Pb 2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid lead metal. II.At the anode pale green chlorine gas. b)To determine the products of electrolysis of molten Zinc bromide
4 (i)Decomposition of electrolyte into free ions; ZnBr2 (l) -> Zn 2+(l) + 2Br-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Zn 2+(l) + 2e -> Zn(l) (Cation / Zn2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Br-(l) -> Br2 (g) + 2e (Anion / Br- donate/lose electrons to form free atom then a liquid molecule which change to gas on heating) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid Zinc metal. II.At the anode red bromine liquid / red/brown bromine gas.


II.At the anode pale green chlorine gas. b)To determine the products of electrolysis of molten Zinc bromide
4 (i)Decomposition of electrolyte into free ions; ZnBr2 (l) -> Zn 2+(l) + 2Br-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Zn 2+(l) + 2e -> Zn(l) (Cation / Zn2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Br-(l) -> Br2 (g) + 2e (Anion / Br- donate/lose electrons to form free atom then a liquid molecule which change to gas on heating) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid Zinc metal. II.At the anode red bromine liquid / red/brown bromine gas. c)To determine the products of electrolysis of molten sodium chloride (i)Decomposition of electrolyte into free ions; NaCl (l) -> Na +(l) + Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); 2Na+(l) + 2e -> Na (l) (Cation / Na+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid sodium metal. II.At the anode pale green chlorine gas.


II.At the anode red bromine liquid / red/brown bromine gas. c)To determine the products of electrolysis of molten sodium chloride (i)Decomposition of electrolyte into free ions; NaCl (l) -> Na +(l) + Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); 2Na+(l) + 2e -> Na (l) (Cation / Na+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid sodium metal. II.At the anode pale green chlorine gas. d)To determine the products of electrolysis of molten Aluminium (III)oxide (i)Decomposition of electrolyte into free ions; Al2O3 (l) -> 2Al 3+(l) + 3O2-(l) (Compound decomposed into free cation and anion in liquid state)
5 (ii)At the cathode/negative electrode(-); 4Al 3+ (l) + 12e -> 4Al (l) (Cation / Al 3+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 6O2-(l) -> 3O2 (g) + 12e (Anion /6O2- donate/lose 12 electrons to form free atom then three gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid aluminium metal. II.At the anode colourless gas that relights/rekindles glowing splint. 13.In industries electrolysis has the following uses/applications: (a)Extraction of reactive metals from their ores. Potassium, sodium ,magnesium, and aluminium are extracted from their ores using electrolytic methods. (b)Purifying copper after exraction from copper pyrites ores. Copper obtained from copper pyrites ores is not pure.


Potassium, sodium ,magnesium, and aluminium are extracted from their ores using electrolytic methods. (b)Purifying copper after exraction from copper pyrites ores. Copper obtained from copper pyrites ores is not pure. After extraction, the copper is refined by electrolysing copper(II)sulphate(VI) solution using the impure copper as anode and a thin strip of pure copper as cathode. Electrode ionization take place there: (i)At the cathode; Cu2+ (aq) + 2e -> Cu(s) (Pure copper deposits on the strip (ii)At the anode; Cu(s) ->Cu2+ (aq) + 2e (impure copper erodes/dissolves) (c)Electroplating The label EPNS(Electro Plated Nickel Silver) on some steel/metallic utensils mean they are plated/coated with silver and/or Nickel to improve their appearance(add their aesthetic value)and prevent/slow corrosion(rusting of iron). Electroplating is the process of coating a metal with another metal using an electric current. During electroplating, the cathode is made of the metal to be coated/impure. Example: During the electroplating of a spoon with silver (i)the spoon/impure is placed as the cathode(negative terminal of battery) (ii)the pure silver is placed as the anode(positive terminal of battery) (iii)the pure silver erodes/ionizes/dissociates to release electrons: Ag(s) ->Ag+ (aq) + e (impure silver erodes/dissolves)
6 (iv) silver (Ag+)ions from electrolyte gain electrons to form pure silver deposits / coat /cover the spoon/impure Ag+ (aq) + e ->Ag(s) (pure silver deposits /coat/cover on spoon)
CARBON AND ITS COMPOUNDS Carbon is an element in Group IV(Group 4)of the Periodic table .It has atomic number 6 and electronic configuration 2:4 and thus has four valence electrons (tetravalent).It does not easily ionize but forms strong covalent bonds with other elements including itself. (a)Occurrence Carbon mainly naturally occurs as: (i)allotropes of carbon i.e graphite, diamond and fullerenes. (ii)amorphous carbon in coal, peat ,charcoal and coke.


Example: During the electroplating of a spoon with silver (i)the spoon/impure is placed as the cathode(negative terminal of battery) (ii)the pure silver is placed as the anode(positive terminal of battery) (iii)the pure silver erodes/ionizes/dissociates to release electrons: Ag(s) ->Ag+ (aq) + e (impure silver erodes/dissolves)
6 (iv) silver (Ag+)ions from electrolyte gain electrons to form pure silver deposits / coat /cover the spoon/impure Ag+ (aq) + e ->Ag(s) (pure silver deposits /coat/cover on spoon)
CARBON AND ITS COMPOUNDS Carbon is an element in Group IV(Group 4)of the Periodic table .It has atomic number 6 and electronic configuration 2:4 and thus has four valence electrons (tetravalent).It does not easily ionize but forms strong covalent bonds with other elements including itself. (a)Occurrence Carbon mainly naturally occurs as: (i)allotropes of carbon i.e graphite, diamond and fullerenes. (ii)amorphous carbon in coal, peat ,charcoal and coke. (iii)carbon(IV)oxide gas accounting 0.03% by volume of normal air in the atmosphere. (b)Allotropes of Carbon Carbon naturally occur in two main crystalline allotropic forms, carbon-graphite and carbon-diamond Carbon-diamond Carbon-graphite Shiny crystalline solid Black/dull crystalline solid Has a very high melting/boiling point because it has a very closely packed giant tetrahedral structure joined by strong covalent bonds Has a high melting/boiling point because it has a very closely packed giant hexagonal planar structure joined by strong covalent bonds Has very high density(Hardest known Soft
2 natural substance) Abrassive Slippery Poor electrical conductor because it has no free delocalized electrons Good electrical conductor because it has free 4th valency delocalized electrons Is used in making Jewels, drilling and cutting metals Used in making Lead-pencils,electrodes in batteries and as a lubricant Has giant tetrahedral structure Has giant hexagonal planar structure c)Properties of Carbon (i)Physical properties of carbon Carbon occur widely and naturally as a black solid It is insoluble in water but soluble in carbon disulphide and organic solvents.


(ii)amorphous carbon in coal, peat ,charcoal and coke. (iii)carbon(IV)oxide gas accounting 0.03% by volume of normal air in the atmosphere. (b)Allotropes of Carbon Carbon naturally occur in two main crystalline allotropic forms, carbon-graphite and carbon-diamond Carbon-diamond Carbon-graphite Shiny crystalline solid Black/dull crystalline solid Has a very high melting/boiling point because it has a very closely packed giant tetrahedral structure joined by strong covalent bonds Has a high melting/boiling point because it has a very closely packed giant hexagonal planar structure joined by strong covalent bonds Has very high density(Hardest known Soft
2 natural substance) Abrassive Slippery Poor electrical conductor because it has no free delocalized electrons Good electrical conductor because it has free 4th valency delocalized electrons Is used in making Jewels, drilling and cutting metals Used in making Lead-pencils,electrodes in batteries and as a lubricant Has giant tetrahedral structure Has giant hexagonal planar structure c)Properties of Carbon (i)Physical properties of carbon Carbon occur widely and naturally as a black solid It is insoluble in water but soluble in carbon disulphide and organic solvents. It is a poor electrical and thermal conductor. (ii)Chemical properties of carbon I. Burning Experiment Introduce a small piece of charcoal on a Bunsen flame then lower it into a gas jar containing Oxygen gas. Put three drops of water. Swirl. Test the solution with blue and red litmus papers. Observation -Carbon chars then burns with a blue flame -Colourless and odourless gas produced -Solution formed turn blue litmus paper faint red. Red litmus paper remains red. Explanation Carbon burns in air and faster in Oxygen with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon burns in limited supply of air with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon (IV) oxide gas dissolve in water to form weak acidic solution of Carbonic (IV)acid.


Explanation Carbon burns in air and faster in Oxygen with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon burns in limited supply of air with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon (IV) oxide gas dissolve in water to form weak acidic solution of Carbonic (IV)acid. Chemical Equation C(s) + O2(g) -> CO2(g) (in excess air) 2C(s) + O2(g) -> 2CO(g) (in limited air) CO2(g) + H2O (l) -> H2CO3 (aq) (very weak acid) II. Reducing agent Experiment Mix thoroughly equal amounts of powdered charcoal and copper (II)oxide into a crucible. Heat strongly. Observation Colour change from black to brown Explanation
3 Carbon is a reducing agent. For ages it has been used to reducing metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas.


Heat strongly. Observation Colour change from black to brown Explanation
3 Carbon is a reducing agent. For ages it has been used to reducing metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas. Carbon reduces black copper(II)oxide to brown copper metal Chemical Equation 2CuO(s) + C(s) -> 2Cu(s) + CO2(g) (black) (brown) 2PbO(s) + C(s) -> 2Pb(s) + CO2(g) (brown when hot/ (grey) yellow when cool) 2ZnO(s) + C(s) -> 2Zn(s) + CO2(g) (yellow when hot/ (grey) white when cool) Fe2O3(s) + 3C(s) -> 2Fe(s) + 3CO2(g) (brown when hot/cool (grey) Fe3O4 (s) + 4C(s) -> 3Fe(s) + 4CO2(g) (brown when hot/cool (grey)
4 B: COMPOUNDS OF CARBON The following are the main compounds of Carbon (i)Carbon(IV)Oxide(CO2) (ii)Carbon(II)Oxide(CO) (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) (iv)Sodium carbonate(Na2CO3) (i) Carbon(IV)Oxide (CO2) (a)Occurrence Carbon(IV)oxide is found: -in the air /atmosphere as 0.03% by volume. -a solid carbon(IV)oxide mineral in Esageri near Eldame Ravine and Kerita near Limuru in Kenya. (b)School Laboratory preparation In the school laboratory carbon(IV)oxide can be prepared in the school laboratory from the reaction of marble chips(CaCO3)or sodium hydrogen carbonate(NaHCO3) with dilute hydrochloric acid. 5 (c)Properties of carbon(IV)oxide gas(Questions) 1.Write the equation for the reaction for the school laboratory preparation of carbon (IV)oxide gas. Any carbonate reacted with dilute hydrochloric acid should be able to generate carbon (IV)oxide gas.


(b)School Laboratory preparation In the school laboratory carbon(IV)oxide can be prepared in the school laboratory from the reaction of marble chips(CaCO3)or sodium hydrogen carbonate(NaHCO3) with dilute hydrochloric acid. 5 (c)Properties of carbon(IV)oxide gas(Questions) 1.Write the equation for the reaction for the school laboratory preparation of carbon (IV)oxide gas. Any carbonate reacted with dilute hydrochloric acid should be able to generate carbon (IV)oxide gas. Chemical equations CaCO3(s) + 2HCl(aq) -> CaCO3 (aq) + H2O(l) + CO2 (g) ZnCO3(s) + 2HCl(aq) -> ZnCO3 (aq) + H2O(l) + CO2 (g) MgCO3(s) + 2HCl(aq) -> MgCO3 (aq) + H2O(l) + CO2 (g) CuCO3(s) + 2HCl(aq) -> CuCO3 (aq) + H2O(l) + CO2 (g) NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) KHCO3(s) + HCl(aq) -> K2CO3 (aq) + H2O(l) + CO2 (g) 2.What method of gas collection is used in preparation of Carbon(IV)oxide gas. Explain. Downward delivery /upward displacement of air/over mercury Carbon(IV)oxide gas is about 1½ times denser than air. 3.What is the purpose of : (a)water? To absorb the more volatile hydrogen chloride fumes produced during the vigorous reaction. (b)sodium hydrogen carbonate? To absorb the more volatile hydrogen chloride fumes produced during the vigorous reaction and by reacting with the acid to produce more carbon (IV)oxide gas . 6 Chemical equation NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) (c)concentrated sulphuric(VI)acid? To dry the gas/as a drying agent 4.Describe the smell of carbon(IV)oxide gas Colourless and odourless 5. Effect on lime water.


6 Chemical equation NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) (c)concentrated sulphuric(VI)acid? To dry the gas/as a drying agent 4.Describe the smell of carbon(IV)oxide gas Colourless and odourless 5. Effect on lime water. Experiment Bubbled carbon(IV)oxide gas into a test tube containing lime water for about three minutes Observation White precipitate is formed. White precipitate dissolved when excess carbon(IV)oxide gas is bubbled . Explanation Carbon(IV)oxide gas reacts with lime water(Ca(OH)2) to form an insoluble white precipitate of calcium carbonate. Calcium carbonate reacts with more Carbon(IV) oxide gas to form soluble Calcium hydrogen carbonate. Chemical equation Ca(OH)2(aq) + CO2 (g) -> CaCO3 (s) + H2O(l) CaCO3 (aq) + H2O(l) + CO2 (g) -> Ca(HCO3) 2 (aq) 6. Effects on burning Magnesium ribbon Experiment Lower a piece of burning magnesium ribbon into a gas jar containing carbon (IV)oxide gas. Observation The ribbon continues to burn with difficulty White ash/solid is formed. Black speck/solid/particles formed on the side of gas jar. Explanation Carbon(IV)oxide gas does not support combustion/burning.Magnesium burn to produce/release enough heat energy to decompose Carbon(IV) oxide gas to carbon and oxygen.Magnesium continues to burn in Oxygen forming white Magnesium Oxide solid/ash.Black speck/particle of carbon/charcoal residue forms on the sides of reaction flask. During the reaction Carbon(IV) oxide is reduced(Oxidizing agent)to carbon while Magnesium is Oxidized to Magnesium Oxide. Chemical equation 2Mg(s) + CO2 (g) -> C (s) + 2MgO(l)
7 7. Dry and wet litmus papers were separately put in a gas jar containing dry carbon (IV)oxide gas. State and explain the observations made.


Chemical equation 2Mg(s) + CO2 (g) -> C (s) + 2MgO(l)
7 7. Dry and wet litmus papers were separately put in a gas jar containing dry carbon (IV)oxide gas. State and explain the observations made. Observation Blue dry litmus paper remain blue Red dry litmus paper remain Red Blue wet/damp/moist litmus paper turn red Red wet/damp/moist litmus paper remain red Explanation Dry Carbon (IV) oxide gas is a molecular compound that does not dissociate/ionize to release H+ and thus has no effect on litmus papers. Wet/damp/moist litmus papers contains water that dissolves/react with dry carbon (IV) oxide gas to form the weak solution of carbonic (IV) acid(H2CO3). Carbonic (IV) acid dissociate/ionizes to a few /little free H+ and CO32-. The few H+ (aq) ions are responsible for turning blue litmus paper to faint red showing the gas is very weakly acidic. Chemical equation H2CO3(aq) -> 2H+ (aq) + CO32-(aq) 8. Explain why Carbon (IV)oxide cannot be prepared from the reaction of: (i) marble chips with dilute sulphuric(VI)acid. Explanation Reaction forms insoluble calcium sulphate(VI)that cover/coat unreacted marble chips stopping further reaction Chemical equation CaCO3(s) + H2SO4 (aq) -> CaSO4 (s) + H2O(l) + CO2 (g) PbCO3(s) + H2SO4 (aq) -> PbSO4 (s) + H2O(l) + CO2 (g) BaCO3(s) + H2SO4 (aq) -> BaSO4 (s) + H2O(l) + CO2 (g) (ii) Lead(II)carbonate with dilute Hydrochloric acid. Reaction forms insoluble Lead(II)Chloride that cover/coat unreacted Lead(II) carbonate stopping further reaction unless the reaction mixture is heated. Lead(II)Chloride is soluble in hot water. Chemical equation PbCO3(s) + 2HCl (aq) -> PbCl2 (s) + H2O(l) + CO2 (g) 9.


Reaction forms insoluble Lead(II)Chloride that cover/coat unreacted Lead(II) carbonate stopping further reaction unless the reaction mixture is heated. Lead(II)Chloride is soluble in hot water. Chemical equation PbCO3(s) + 2HCl (aq) -> PbCl2 (s) + H2O(l) + CO2 (g) 9. Describe the test for the presence of Carbon (IV)oxide. Using burning splint Lower a burning splint into a gas jar suspected to contain Carbon (IV)oxide gas.The burning splint is extinguished. Using Lime water. Bubble the gas suspected to be Carbon (IV)oxide gas.A white precipitate that dissolve in excess bubbling is formed. 8 Chemical equation Ca(OH)2(aq) + CO2 (g) -> CaCO3 (s) + H2O(l) CaCO3 (aq) + H2O(l) + CO2 (g) -> Ca(HCO3) 2 (aq) 10.State three main uses of Carbon (IV)oxide gas (i)In the Solvay process for the manufacture of soda ash/sodium carbonate (ii)In preservation of aerated drinks (iii)As fire extinguisher because it does not support combustion and is denser than air. (iv)In manufacture of Baking powder. (ii) Carbon(II)Oxide (CO) (a)Occurrence Carbon(II)oxide is found is found from incomplete combustion of fuels like petrol charcoal, liquefied Petroleum Gas/LPG. (b)School Laboratory preparation In the school laboratory carbon(II)oxide can be prepared from dehydration of methanoic acid/Formic acid(HCOOH) or Ethan-1,2-dioic acid/Oxalic acid(HOOCCOOH) using concentrated sulphuric(VI) acid. Heating is necessary.


(ii) Carbon(II)Oxide (CO) (a)Occurrence Carbon(II)oxide is found is found from incomplete combustion of fuels like petrol charcoal, liquefied Petroleum Gas/LPG. (b)School Laboratory preparation In the school laboratory carbon(II)oxide can be prepared from dehydration of methanoic acid/Formic acid(HCOOH) or Ethan-1,2-dioic acid/Oxalic acid(HOOCCOOH) using concentrated sulphuric(VI) acid. Heating is necessary. METHOD 1:Preparation of Carbon (IV)Oxide from dehydration of Oxalic/ethan-1,2-dioic acid METHOD 2:Preparation of Carbon (IV)Oxide from dehydration of Formic/Methanoic acid
9 (c)Properties of Carbon (II)Oxide(Questions) 1.Write the equation for the reaction for the preparation of carbon(II)oxide using; (i)Method 1; Chemical equation HOOCCOOH(s) –Conc.H2SO4--> CO(g) + CO2 (g) + H2O(l) H2C2O4(s) –Conc.H2SO4--> CO(g) + CO2 (g) + H2O(l) (ii)Method 2; Chemical equation HCOOH(s) –Conc.H2SO4--> CO(g) + H2O(l) H2CO2(s) –Conc.H2SO4--> CO(g) + H2O(l) 2.What method of gas collection is used during the preparation of carbon (II) oxide. Over water because the gas is insoluble in water. Downward delivery because the gas is 1 ½ times denser than air . 3.What is the purpose of : (i) Potassium hydroxide/sodium hydroxide in Method 1 To absorb/ remove carbon (II) oxide produced during the reaction. 2KOH (aq) + CO2 (g) -> K2CO3 (s) + H2O(l) 2NaOH (aq) + CO2 (g) -> Na2CO3 (s) + H2O(l) (ii) Concentrated sulphuric(VI)acid in Method 1 and 2.


Downward delivery because the gas is 1 ½ times denser than air . 3.What is the purpose of : (i) Potassium hydroxide/sodium hydroxide in Method 1 To absorb/ remove carbon (II) oxide produced during the reaction. 2KOH (aq) + CO2 (g) -> K2CO3 (s) + H2O(l) 2NaOH (aq) + CO2 (g) -> Na2CO3 (s) + H2O(l) (ii) Concentrated sulphuric(VI)acid in Method 1 and 2. Dehydrating agent –removes the element of water (Hydrogen and Oxygen in ratio 2:1) present in both methanoic and ethan-1,2-dioic acid. 10 4. Describe the smell of carbon(II)oxide. Colourless and odourless. 5. State and explain the observation made when carbon(IV)oxide is bubbled in lime water for a long time. No white precipitate is formed. 6. Dry and wet/moist/damp litmus papers were separately put in a gas jar containing dry carbon(IV)oxide gas. State and explain the observations made. Observation -blue dry litmus paper remains blue -red dry litmus paper remains red - wet/moist/damp blue litmus paper remains blue - wet/moist/damp red litmus paper remains red Explanation Carbon(II)oxide gas is a molecular compound that does not dissociate /ionize to release H+ ions and thus has no effect on litmus papers. Carbon(II)oxide gas is therefore a neutral gas. 7. Carbon (II)oxide gas was ignited at the end of a generator as below. (i)State the observations made in flame K. Gas burns with a blue flame (ii)Write the equation for the reaction taking place at flame K. 2CO(g) + O2 (g) -> 2CO2 (g) 8. Carbon(II)oxide is a reducing agent. Explain Experiment Pass carbon(II)oxide through glass tube containing copper (II)oxide. Ignite any excess poisonous carbon(II)oxide. Observation Colour change from black to brown. Excess carbon (II)oxide burn with a blue flame. Flame K Dry carbon(II)oxide
11 Explanation Carbon is a reducing agent.


Observation Colour change from black to brown. Excess carbon (II)oxide burn with a blue flame. Flame K Dry carbon(II)oxide
11 Explanation Carbon is a reducing agent. It is used to reduce metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas. Carbon(II)Oxide reduces black copper(II)oxide to brown copper metal Chemical Equation CuO(s) + CO(g) -> Cu(s) + CO2(g) (black) (brown) PbO(s) + CO(g) -> Pb(s) + CO2(g) (brown when hot/ (grey) yellow when cool) ZnO(s) + CO(g) -> Zn(s) + CO2(g) (yellow when hot/ (grey) white when cool) Fe2O3(s) + 3CO(s) -> 2Fe(s) + 3CO2(g) (brown when hot/cool (grey) Fe3O4 (s) + 4CO(g) -> 3Fe(s) + 4CO2(g) (brown when hot/cool (grey) These reaction are used during the extraction of many metals from their ore. 9. Carbon (II) oxide is a pollutant. Explain. Carbon(II)oxide is highly poisonous/toxic.It preferentially combine with haemoglobin to form stable carboxyhaemoglobin in the blood instead of oxyhaemoglobin.This reduces the free haemoglobin in the blood causing nausea , coma then death. 10.The diagram below show a burning charcoal stove/burner/jiko. Use it to answer the questions that follow. 12 Explain the changes that take place in the burner Explanation Charcoal stove has air holes through which air enters. Air oxidizes carbon to carbon(IV)oxide gas at region I. This reaction is exothermic(-∆H) producing more heat. Chemical equation C(s) + O2(g) -> CO2(g) Carbon(IV)oxide gas formed rises up to meet more charcoal which reduces it to Carbon(II)oxide gas. Chemical equation 2CO2 (g) + O2(g) -> 2CO (g) At the top of burner in region II, Carbon (II)oxide gas is further oxidized to Carbon(IV)oxide gas if there is plenty of air but escape if the air is limited poisoning the living things around.


This reaction is exothermic(-∆H) producing more heat. Chemical equation C(s) + O2(g) -> CO2(g) Carbon(IV)oxide gas formed rises up to meet more charcoal which reduces it to Carbon(II)oxide gas. Chemical equation 2CO2 (g) + O2(g) -> 2CO (g) At the top of burner in region II, Carbon (II)oxide gas is further oxidized to Carbon(IV)oxide gas if there is plenty of air but escape if the air is limited poisoning the living things around. Chemical equation 2CO (g) + O2(g) -> 2CO2 (g) (excess air) 11.Describe the test for the presence of carbon(II)oxide gas. Experiment Burn/Ignite the pure sample of the gas. Pass/Bubble the products into lime water/Calcium hydroxide . Observation Colourless gas burns with a blue flame. A white precipitate is formed that dissolve on further bubbling of the products. Chemical equation 2CO (g) + O2(g) -> 2CO2 (g) (gas burns with blue flame) Chemical equation Ca(OH) 2 (aq) + CO2 (g) -> CaCO3 (s) + H2O(l) Chemical equation CO2 (g) + CaCO3 (s) + H2O(l) -> Ca(HCO3) 2 (aq) 12. State the main uses of carbon (II)oxide gas. (i) As a fuel /water gas (ii)As a reducing agent in the blast furnace for extracting iron from iron ore(Magnetite/Haematite) (iii)As a reducing agent in extraction of Zinc from Zinc ore/Zinc blende (iv) As a reducing agent in extraction of Lead from Lead ore/Galena (v) As a reducing agent in extraction of Copper from Copper iron sulphide/Copper pyrites. 13 (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) 1.Carbonate (IV) (CO32-) are normal salts derived from carbonic(IV)acid (H2CO3) and hydrogen carbonate (IV) (HCO3-) are acid salts derived from carbonic(IV)acid.


State the main uses of carbon (II)oxide gas. (i) As a fuel /water gas (ii)As a reducing agent in the blast furnace for extracting iron from iron ore(Magnetite/Haematite) (iii)As a reducing agent in extraction of Zinc from Zinc ore/Zinc blende (iv) As a reducing agent in extraction of Lead from Lead ore/Galena (v) As a reducing agent in extraction of Copper from Copper iron sulphide/Copper pyrites. 13 (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) 1.Carbonate (IV) (CO32-) are normal salts derived from carbonic(IV)acid (H2CO3) and hydrogen carbonate (IV) (HCO3-) are acid salts derived from carbonic(IV)acid. Carbonic(IV)acid(H2CO3) is formed when carbon(IV)oxide gas is bubbled in water. It is a dibasic acid with two ionizable hydrogens. H2CO3(aq) ->2H+(aq) + CO32-(aq) H2CO3(aq) -> H+(aq) + HCO3 - (aq) 2.Carbonate (IV) (CO32-) are insoluble in water except Na2CO3 , K2CO3 and (NH4)2CO3 3.Hydrogen carbonate (IV) (HCO3-) are soluble in water. Only five hydrogen carbonates exist. Na HCO3 , KHCO3 ,NH4HCO3 Ca(HCO3)2 and Mg(HCO3)2 Ca(HCO3)2 and Mg(HCO3)2 exist only in aqueous solutions. 3.The following experiments show the effect of heat on Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts: Experiment In a clean dry test tube place separately about 1.0 of the following: Zinc(II)carbonate(IV), sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) ammonium carbonate(IV), potassium hydrogen carbonate(IV), Lead(II)carbonate(IV), Iron(II)carbonate(IV), and copper(II)carbonate(IV). Heat each portion gently the strongly. Test any gases produced with lime water.


3.The following experiments show the effect of heat on Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts: Experiment In a clean dry test tube place separately about 1.0 of the following: Zinc(II)carbonate(IV), sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) ammonium carbonate(IV), potassium hydrogen carbonate(IV), Lead(II)carbonate(IV), Iron(II)carbonate(IV), and copper(II)carbonate(IV). Heat each portion gently the strongly. Test any gases produced with lime water. Observation (i)Colorless droplets form on the cooler parts of test tube in case of sodium carbonate(IV) and Potassium carbonate(IV). (ii)White residue/solid left in case of sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) and potassium hydrogen carbonate(IV). (iii)Colour changes from blue/green to black in case of copper(II)carbonate(IV). (iv) Colour changes from green to brown/yellow in case of Iron (II)carbonate(IV). (v) Colour changes from white when cool to yellow when hot in case of Zinc (II) carbonate(IV). (vi) Colour changes from yellow when cool to brown when hot in case of Lead (II) carbonate(IV). (vii)Colourless gas produced that forms a white precipitate with lime water in all cases. Explanation 1. Sodium carbonate(IV) and Potassium carbonate(IV) exist as hydrated salts with 10 molecules of water of crystallization that condenses and collects on cooler parts of test tube as a colourless liquid. Chemical equation Na2CO3 .10H2O(s) -> Na2CO3 (s) + 10H2O(l)
14 K2CO3 .10H2O(s) -> K2CO3 (s) + 10H2O(l) 2. Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts decompose on heating except Sodium carbonate(IV) and Potassium carbonate(IV). (a) Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV) decompose on heating to form sodium carbonate(IV) and Potassium carbonate(IV).Water and carbon(IV)oxide gas are also produced.


Chemical equation Na2CO3 .10H2O(s) -> Na2CO3 (s) + 10H2O(l)
14 K2CO3 .10H2O(s) -> K2CO3 (s) + 10H2O(l) 2. Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts decompose on heating except Sodium carbonate(IV) and Potassium carbonate(IV). (a) Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV) decompose on heating to form sodium carbonate(IV) and Potassium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation 2NaHCO3 (s) -> Na2CO3 (s) + H2O(l) + CO2 (g) (white) (white) 2KHCO3 (s) -> K2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (b) Calcium hydrogen carbonate(IV) and Magnesium hydrogen carbonate(IV) decompose on heating to form insoluble Calcium carbonate(IV) and Magnesium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g.


Chemical equation 2NaHCO3 (s) -> Na2CO3 (s) + H2O(l) + CO2 (g) (white) (white) 2KHCO3 (s) -> K2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (b) Calcium hydrogen carbonate(IV) and Magnesium hydrogen carbonate(IV) decompose on heating to form insoluble Calcium carbonate(IV) and Magnesium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g. Chemical equation MgCO3 (s) -> MgO (s) + CO2 (g) (white solid) (white solid) Chemical equation BaCO3 (s) -> BaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CaCO3 (s) -> CaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CuCO3 (s) -> CuO (s) + CO2 (g) (blue/green solid) (black solid) Chemical equation ZnCO3 (s) -> ZnO (s) + CO2 (g) (white solid) (white solid when cool/
15 Yellow solid when hot) Chemical equation PbCO3 (s) -> PbO (s) + CO2 (g) (white solid) (yellow solid when cool/ brown solid when hot) 4.The following experiments show the presence of Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) ions in sample of a salt: (a)Using Lead(II) nitrate(V) I.


Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g. Chemical equation MgCO3 (s) -> MgO (s) + CO2 (g) (white solid) (white solid) Chemical equation BaCO3 (s) -> BaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CaCO3 (s) -> CaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CuCO3 (s) -> CuO (s) + CO2 (g) (blue/green solid) (black solid) Chemical equation ZnCO3 (s) -> ZnO (s) + CO2 (g) (white solid) (white solid when cool/
15 Yellow solid when hot) Chemical equation PbCO3 (s) -> PbO (s) + CO2 (g) (white solid) (yellow solid when cool/ brown solid when hot) 4.The following experiments show the presence of Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) ions in sample of a salt: (a)Using Lead(II) nitrate(V) I. Using a portion of salt solution in a test tube .add four drops of Lead(II)nitrate(V)solution.Preserve. Observation inference White precipitate/ppt CO32- ,SO32- ,SO42- ,Cl- - II. To the preserved solution ,add six drops of dilutte nitric(V)acid. Preserve.


Observation inference White precipitate/ppt CO32- ,SO32- ,SO42- ,Cl- - II. To the preserved solution ,add six drops of dilutte nitric(V)acid. Preserve. Observation inference White precipitate/ppt persists White precipitate/ppt dissolves SO42- ,Cl- CO32- ,SO32- II. To the preserved sample( that forms a precipitate ),heat to boil. Observation inference White precipitate/ppt persists White precipitate/ppt dissolves SO42- Cl- II. To the preserved sample( that do not form a precipitate ),add three drops of acidified potassium manganate(VII)/lime water Observation inference Effervescence/bubbles/fizzing colourless gas produced Acidified KMnO4 decolorized/no white precipitate on lime water Effervescence/bubbles/fizzing colourless gas produced Acidified KMnO4 not decolorized/ white precipitate on lime water SO32- CO32-
16 Experiments/Observations: (b)Using Barium(II)nitrate(V)/ Barium(II)chloride I. To about 5cm3 of a salt solution in a test tube add four drops of Barium(II) nitrate (V) / Barium(II)chloride. Preserve. Observation Inference White precipitate/ppt SO42- , SO32- , CO32- ions II. To the preserved sample in (I) above, add six drops of 2M nitric(V) acid . Preserve. Observation 1 Observation Inference White precipitate/ppt persists SO42- , ions Observation 2 Observation Inference White precipitate/ppt dissolves SO32- , CO32- , ions III.To the preserved sample observation 2 in (II) above, add 4 drops of acidified potassium manganate(VII) /dichromate(VI).


To the preserved sample in (I) above, add six drops of 2M nitric(V) acid . Preserve. Observation 1 Observation Inference White precipitate/ppt persists SO42- , ions Observation 2 Observation Inference White precipitate/ppt dissolves SO32- , CO32- , ions III.To the preserved sample observation 2 in (II) above, add 4 drops of acidified potassium manganate(VII) /dichromate(VI). Observation 1 Observation Inference (i)acidified potassium manganate(VII)decolorized (ii)Orange colour of acidified potassium dichromate(VI) turns to green SO32- ions Observation 2 Observation Inference (i)acidified potassium manganate(VII) not decolorized (ii)Orange colour of acidified potassium dichromate(VI) does not turns to green CO32- ions Explanations Using Lead(II)nitrate(V)
17 (i)Lead(II)nitrate(V) solution reacts with chlorides(Cl-), Sulphate (VI) salts (SO42- ), Sulphate (IV)salts (SO32-) and carbonates(CO32-) to form the insoluble white precipitate of Lead(II)chloride, Lead(II)sulphate(VI), Lead(II) sulphate (IV) and Lead(II)carbonate(IV). Chemical/ionic equation: Pb2+(aq) + Cl- (aq) -> PbCl2(s) Pb2+(aq) + SO42+ (aq) -> PbSO4 (s) Pb2+(aq) + SO32+ (aq) -> PbSO3 (s) Pb2+(aq) + CO32+ (aq) -> PbCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Lead(II)chloride and Lead(II)sulphate(VI) do not react with the acid and thus their white precipitates remain/ persists. - Lead(II) sulphate (IV) and Lead(II)carbonate(IV) reacts with the acid to form soluble Lead(II) nitrate (V) and produce/effervesces/fizzes/bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. .


Chemical/ionic equation: Pb2+(aq) + Cl- (aq) -> PbCl2(s) Pb2+(aq) + SO42+ (aq) -> PbSO4 (s) Pb2+(aq) + SO32+ (aq) -> PbSO3 (s) Pb2+(aq) + CO32+ (aq) -> PbCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Lead(II)chloride and Lead(II)sulphate(VI) do not react with the acid and thus their white precipitates remain/ persists. - Lead(II) sulphate (IV) and Lead(II)carbonate(IV) reacts with the acid to form soluble Lead(II) nitrate (V) and produce/effervesces/fizzes/bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. . Chemical/ionic equation: PbSO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + SO2 (g) PbCO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + CO2 (g) (iii)When Lead(II)chloride and Lead(II)sulphate(VI) are heated/warmed; - Lead(II)chloride dissolves in hot water/on boiling(recrystallizes on cooling) - Lead(II)sulphate(VI) do not dissolve in hot water thus its white precipitate persists/remains on heating/boiling. (iv)When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not.


Chemical/ionic equation: PbSO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + SO2 (g) PbCO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + CO2 (g) (iii)When Lead(II)chloride and Lead(II)sulphate(VI) are heated/warmed; - Lead(II)chloride dissolves in hot water/on boiling(recrystallizes on cooling) - Lead(II)sulphate(VI) do not dissolve in hot water thus its white precipitate persists/remains on heating/boiling. (iv)When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l) These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water.


Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l) These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water. 18 Using Barium(II)nitrate(V)/ Barium(II)Chloride (i)Barium(II)nitrate(V) and/ or Barium(II)chloride solution reacts with Sulphate (VI) salts (SO42- ), Sulphate (IV)salts (SO32-) and carbonates(CO32-) to form the insoluble white precipitate of Barium(II)sulphate(VI), Barium(II) sulphate (IV) and Barium(II)carbonate(IV). Chemical/ionic equation: Ba2+(aq) + SO42+ (aq) -> BaSO4 (s) Ba2+(aq) + SO32+ (aq) -> BaSO3 (s) Ba2+(aq) + CO32+ (aq) -> BaCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Barium (II)sulphate(VI) do not react with the acid and thus its white precipitates remain/ persists. - Barium(II) sulphate (IV) and Barium(II)carbonate(IV) reacts with the acid to form soluble Barium(II) nitrate (V) and produce /effervesces /fizzes/ bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. .


Chemical/ionic equation: Ba2+(aq) + SO42+ (aq) -> BaSO4 (s) Ba2+(aq) + SO32+ (aq) -> BaSO3 (s) Ba2+(aq) + CO32+ (aq) -> BaCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Barium (II)sulphate(VI) do not react with the acid and thus its white precipitates remain/ persists. - Barium(II) sulphate (IV) and Barium(II)carbonate(IV) reacts with the acid to form soluble Barium(II) nitrate (V) and produce /effervesces /fizzes/ bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. . Chemical/ionic equation: BaSO3 (s) + 2H+(aq) -> H2 O (l) + Ba2+(aq) + SO2 (g) BaCO3 (s) + 2H+(aq) -> H2 O (l) + Ba2+(aq) + CO2 (g) (iii) When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not.


Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l)
19 These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water. (iii) Sodium carbonate(IV) (Na2CO3) (a)Extraction of sodium carbonate from soda ash Sodium carbonate naturally occurs in Lake Magadi in Kenya as Trona.trona is the double salt ; sodium sesquicarbonate. NaHCO3 .Na2CO3 .H2O.It is formed from the volcanic activity that takes place in Lake Naivasha, Nakuru ,Bogoria and Elementeita .All these lakes drain into Lake Magadi through underground rivers. Lake Magadi has no outlet. Solubility of Trona decrease with increase in temperature.High temperature during the day causes trona to naturally crystallize .It is mechanically scooped/dredged/dug and put in a furnace. Inside the furnace, trona decompose into soda ash/sodium carbonate.


Lake Magadi has no outlet. Solubility of Trona decrease with increase in temperature.High temperature during the day causes trona to naturally crystallize .It is mechanically scooped/dredged/dug and put in a furnace. Inside the furnace, trona decompose into soda ash/sodium carbonate. Chemical equation 2NaHCO3 .Na2CO3 .H2O (s) -> 3Na2CO3 (s) + 5H2O(l) + CO2 (g) (trona) (soda ash) Soda ash is then bagged and sold as Magadi soda.It is mainly used: (i)in making glass to lower the melting point of raw materials (sand/SiO2 from 1650oC and CaO from 2500oC to around 1500oC) (ii)in softening hard water (iii)in the manufacture of soapless detergents. (iv)Swimming pool “pH increaser” Sodium chloride is also found dissolved in the lake. Solubility of sodium chloride decrease with decreases in temperature/ sodium chloride has lower solubility at lower temperatures. When temperatures decrease at night it crystallize out .The crystals are then mechanically dug/dredged /scooped then packed for sale as animal/cattle feeds and seasoning food. Summary flow diagram showing the extraction of Soda ash from Trona Sodium chloride and Trona dissolved in the sea Natural fractional crystallization Crystals of Trona (Day time) Dredging /scooping/ digging Crushing Furnace (Heating) Carbon(IV) oxide
20 b)The Solvay process for industrial manufacture of sodium carbonate(IV) (i)Raw materials. -Brine /Concentrated Sodium chloride from salty seas/lakes. -Ammonia gas from Haber. -Limestone /Calcium carbonate from chalk /limestone rich rocks. -Water from rivers/lakes. (ii)Chemical processes Ammonia gas is passed up to meet a downward flow of sodium chloride solution / brine to form ammoniated brine/ammoniacal brine mixture in the ammoniated brine chamber The ammoniated brine mixture is then pumped up, atop the carbonator/ solvay tower. In the carbonator/ solvay tower, ammoniated brine/ammoniacal brine mixture slowly trickle down to meet an upward flow of carbon(IV)oxide gas.


-Water from rivers/lakes. (ii)Chemical processes Ammonia gas is passed up to meet a downward flow of sodium chloride solution / brine to form ammoniated brine/ammoniacal brine mixture in the ammoniated brine chamber The ammoniated brine mixture is then pumped up, atop the carbonator/ solvay tower. In the carbonator/ solvay tower, ammoniated brine/ammoniacal brine mixture slowly trickle down to meet an upward flow of carbon(IV)oxide gas. The carbonator is shelved /packed with quartz/broken glass to (i) reduce the rate of flow of ammoniated brine/ammoniacal brine mixture. (ii)increase surface area of the liquid mixture to ensure a lot of ammoniated brine/ammoniacal brine mixture react with carbon(IV)oxide gas. Insoluble sodium hydrogen carbonate and soluble ammonium chloride are formed from the reaction. Chemical equation CO2(g) + H2O(l) + NaCl (aq) + NH3(g) -> NaHCO3(s) + NH4Cl(aq)
21 The products are then filtered. Insoluble sodium hydrogen carbonate forms the residue while soluble ammonium chloride forms the filtrate. Sodium hydrogen carbonate itself can be used: (i) as baking powder and preservation of some soft drinks. (ii) as a buffer agent and antacid in animal feeds to improve fibre digestion. (iii) making dry chemical fire extinguishers. In the Solvay process Sodium hydrogen carbonate is then heated to form Sodium carbonate/soda ash, water and carbon (IV) oxide gas. Chemical equation 2NaHCO3 (s) -> Na2CO3(s) + CO2(g) + H2O(l) Sodium carbonate is stored ready for use in: (i) during making glass/lowering the melting point of mixture of sand/SiO2 from 1650oC and CaO from 2500oC to around 1500oC (ii) in softening hard water (iii) in the manufacture of soapless detergents. (iv) swimming pool “pH increaser”. Water and carbon(IV)oxide gas are recycled back to the ammoniated brine/ammoniacal brine chamber. More carbon(IV)oxide is produced in the kiln/furnace. Limestone is heated to decompose into Calcium oxide and carbon(IV)oxide.


Water and carbon(IV)oxide gas are recycled back to the ammoniated brine/ammoniacal brine chamber. More carbon(IV)oxide is produced in the kiln/furnace. Limestone is heated to decompose into Calcium oxide and carbon(IV)oxide. Chemical equation CaCO3 (s) -> CaO(s) + CO2(g) Carbon(IV)oxide is recycled to the carbonator/solvay tower. Carbon (IV)oxide is added water in the slaker to form Calcium hydroxide. This process is called slaking. Chemical equation CaO(s) + H2O (l) -> Ca(OH)2 (aq) Calcium hydroxide is mixed with ammonium chloride from the carbonator/solvay tower in the ammonia regeneration chamber to form Calcium chloride , water and more ammonia gas. Chemical equation Ca(OH)2 (aq) +2NH4Cl (aq) -> CaCl2(s) + 2NH3(g) + H2O(l) NH3(g) and H2O(l) are recycled. Calcium chloride may be used: (i)as drying agent in the school laboratory during gas preparation (except ammonia gas)
22 (ii)to lower the melting point of solid sodium chloride / rock salt salts during the Downs process for industrial extraction of sodium metal. Detailed Summary flow diagram of Solvay Process
23 AmmoniatedbrineBrineAmmonia regenerationchamberSolvay Tower/CarbonatorKiln/FurnaceAmmoniumchlorideCarbon(IV)OxideHaberprocessSlakerCalcium hydroxideCalcium oxideWaterSodium hydrogen CarbonateRoasterSodiumcarbonateCalcium chlorideBrine saturated with ammoniaCoke & Limestone
24 Practice 1. The diagram below shows part of the Solvay process used in manufacturing sodium carbonate. Use it to answer the questions that follow. (a)Explain how Sodium Chloride required for this process is obtained from the sea. Sea water is pumped /scooped into shallow pods. Evaporation of most of the water takes place leaving a very concentrated solution. (b)(i) Name process: I. Filtration II.


Evaporation of most of the water takes place leaving a very concentrated solution. (b)(i) Name process: I. Filtration II. Decomposition (ii) Write the equation for the reaction in process: Process I Chemical equation CO2(g) + H2O(l) + NaCl (aq) + NH3(g) -> NaHCO3(s) + NH4Cl(aq) Process II Chemical equation 2NaHCO3 (s) -> Na2CO3(s) + CO2(g) + H2O(l) (c)(i) Name two substances recycled in the solvay process Ammonia gas , Carbon(IV)Oxide and Water. (ii)Which is the by-product of this process? Calcium(II)Chloride /CaCl2 (iii)State two uses that the by-product can be used for: 1. As a drying agent in the school laboratory preparation of gases. 2. In the Downs cell/process for extraction of Sodium to lower the melting point of rock salt. Carbon (IV)oxide Ammonium chloride Process I Saturated sodium chloride solution Ammonia Sodium hydrogen carbonate Process II Sodium carbonate
25 (iv)Write the chemical equation for the formation of the byproducts in the Solvay process. Chemical equation Ca(OH)2 (aq) +2NH4Cl (aq) -> CaCl2(s) + 2NH3(g) + H2O(l) (d)In an experiment to determine the % purity of Sodium carbonate produced in the Solvay process ,2.15g of the sample reacted with exactly 40.0cm3 of 0.5M Sulphuric(VI)acid. (i)Calculate the number of moles of sodium carbonate that reacted. Chemical equation Na2CO3 (aq) +H2SO4 (aq) -> Na2SO4 (aq)+ CO2(g) + H2O(l) Mole ratio Na2CO3 :H2SO4 => 1:1 Moles H2SO4 = Molarity x Volume => 0.5 x 40.0 = 0.02 Moles 1000 1000 Moles of Na2CO3 = 0.02 Moles (ii)Determine the % of sodium carbonate in the sample.


Chemical equation Ca(OH)2 (aq) +2NH4Cl (aq) -> CaCl2(s) + 2NH3(g) + H2O(l) (d)In an experiment to determine the % purity of Sodium carbonate produced in the Solvay process ,2.15g of the sample reacted with exactly 40.0cm3 of 0.5M Sulphuric(VI)acid. (i)Calculate the number of moles of sodium carbonate that reacted. Chemical equation Na2CO3 (aq) +H2SO4 (aq) -> Na2SO4 (aq)+ CO2(g) + H2O(l) Mole ratio Na2CO3 :H2SO4 => 1:1 Moles H2SO4 = Molarity x Volume => 0.5 x 40.0 = 0.02 Moles 1000 1000 Moles of Na2CO3 = 0.02 Moles (ii)Determine the % of sodium carbonate in the sample. Molar mass of Na2CO3 = 106g Mass of Na2CO3 = moles x Molar mass => 0.02 x 106 = 2.12 g % of Na2CO3 = ( 2.12 g x 100) = 98.6047% 2.15 (e) State two uses of soda ash. (i) during making glass/lowering the melting point of mixture of sand/SiO2 from 1650oC and CaO from 2500oC to around 1500oC (ii) in softening hard water (iii) in the manufacture of soapless detergents. (iv) swimming pool “pH increaser”. (f)The diagram below shows a simple ammonia soda tower used in manufacturing sodium carbonate .Use it to answer the questions that follow: Raw materialExcess Carbon(IV)oxide Metal plates Substance
26 (i)Name the raw materials needed in the above process -Ammonia -Water -Carbon(IV)oxide -Limestone -Brine/ Concentrated sodium chloride (ii)Identify substance A Ammonium chloride /NH4Cl (iii) Write the equation for the reaction taking place in: I.Tower.


(i) during making glass/lowering the melting point of mixture of sand/SiO2 from 1650oC and CaO from 2500oC to around 1500oC (ii) in softening hard water (iii) in the manufacture of soapless detergents. (iv) swimming pool “pH increaser”. (f)The diagram below shows a simple ammonia soda tower used in manufacturing sodium carbonate .Use it to answer the questions that follow: Raw materialExcess Carbon(IV)oxide Metal plates Substance
26 (i)Name the raw materials needed in the above process -Ammonia -Water -Carbon(IV)oxide -Limestone -Brine/ Concentrated sodium chloride (ii)Identify substance A Ammonium chloride /NH4Cl (iii) Write the equation for the reaction taking place in: I.Tower. Chemical equation CO2(g) + NaCl (aq) + H2O(l) + NH3(g) -> NaHCO3(s) + NH4Cl(aq) II. Production of excess carbon (IV)oxide. Chemical equation CaCO3 (s) -> CaO(s) + CO2(g) III. The regeneration of ammonia Chemical equation Ca(OH)2 (aq) +2NH4Cl (aq) -> CaCl2(s) + 2NH3(g) + H2O(l) (iv)Give a reason for having the circular metal plates in the tower. -To slow the downward flow of brine. -To increase the rate of dissolving of ammonia. -To increase the surface area for dissolution (v)Name the gases recycled in the process illustrated above. Ammonia gas , Carbon(IV)Oxide and Water. 2. Describe how you would differentiate between carbon (IV)oxide and carbon(II)oxide using chemical method. Method I -Bubble both gases in lime water/Ca(OH)2 -white precipitate is formed if the gas is carbon (IV) oxide - No white precipitate is formed if the gas is carbon (II) oxide Method II
27 -ignite both gases - Carbon (IV) oxide does not burn/ignite - Carbon (II) oxide burn with a blue non-sooty flame. Method III -Lower a burning splint into a gas containing each gas separately.


Describe how you would differentiate between carbon (IV)oxide and carbon(II)oxide using chemical method. Method I -Bubble both gases in lime water/Ca(OH)2 -white precipitate is formed if the gas is carbon (IV) oxide - No white precipitate is formed if the gas is carbon (II) oxide Method II
27 -ignite both gases - Carbon (IV) oxide does not burn/ignite - Carbon (II) oxide burn with a blue non-sooty flame. Method III -Lower a burning splint into a gas containing each gas separately. -burning splint is extinguished if the gas is carbon (IV) oxide -burning splint is not extinguished if the gas is carbon (II) oxide. 3.Using Magnesium sulphate(VI)solution ,describe how you can differentiate between a solution of sodium carbonate from a solution of sodium hydrogen carbonate -Add Magnesium sulphate(VI) solution to separate portions of a solution of sodium carbonate and sodium hydrogen carbonate in separate test tubes -White precipitate is formed in test tube containing sodium carbonate -No white precipitate is formed in test tube containing sodium hydrogen carbonate. Chemical equation Na2CO3 (aq) +MgSO4 (aq) -> Na2SO4 (aq) + MgCO3(s) (white ppt) Ionic equation CO32- (aq) + Mg2+ (aq) -> MgCO3(s) (white ppt) Chemical equation 2NaHCO3 (aq) +MgSO4 (aq) -> Na2SO4 (aq) + Mg(HCO3)2 (aq) (colourless solution) 4. The diagram below shows a common charcoal burner .Assume the burning take place in a room with sufficient supply of air. (a)Explain what happens around:
28 (i)Layer A Sufficient/excess air /oxygen enter through the air holes into the burner .It reacts with/oxidizes Carbon to carbon(IV)oxide Chemical equation C(s) + O2(g) -> CO2 (g) (ii)Layer B Hot carbon(IV)oxide rises up and is reduced by more carbon/charcoal to carbon (II)oxide. Chemical equation C(s) + CO2(g) -> 2CO (g) (ii)Layer C Hot carbon(II)oxide rises up and burns with a blue flame to be oxidized by the excess air to form carbon(IV)oxide.


The diagram below shows a common charcoal burner .Assume the burning take place in a room with sufficient supply of air. (a)Explain what happens around:
28 (i)Layer A Sufficient/excess air /oxygen enter through the air holes into the burner .It reacts with/oxidizes Carbon to carbon(IV)oxide Chemical equation C(s) + O2(g) -> CO2 (g) (ii)Layer B Hot carbon(IV)oxide rises up and is reduced by more carbon/charcoal to carbon (II)oxide. Chemical equation C(s) + CO2(g) -> 2CO (g) (ii)Layer C Hot carbon(II)oxide rises up and burns with a blue flame to be oxidized by the excess air to form carbon(IV)oxide. 2CO (g) + O2(g) -> 2CO2(g) (b)State and explain what would happen if the burner is put in an enclosed room. The hot poisonous /toxic carbon(II)oxide rising up will not be oxidized to Carbon(IV)oxide. (c)Using a chemical test , describe how you would differentiate two unlabelled black solids suspected to be charcoal and copper(II)oxide. Method I -Burn/Ignite the two substances separately. -Charcoal burns with a blue flame - Copper(II)oxide does not burn Method II -Add dilute sulphuric(VI)acid/Nitric(V)acid/Hydrochloric acid separately. -Charcoal does not dissolve. - Copper(II)oxide dissolves to form a colourless solution. 5. Excess Carbon(II)oxide was passed over heated copper(II)oxide as in the set up shown below for five minutes. 29 Dry carbon(IV)oxideHEATCopper(II)oxideBlue flame A (a)State and explain the observations made in the combustion tube. Observation Colour change from black to brown Explanation Carbon (II)oxide reduces black copper(II)oxide to brown copper metal itself oxidized to Carbon(IV)oxide. Chemical equation CO(g) + CuO (s) -> Cu(s) + CO2(g) (black) (brown) (b) (i)Name the gas producing flame A Carbon(II)oxide (ii)Why should the gas be burnt?