id string | question string | answer string | answer_type string | category string | difficulty string | __index_level_0__ int64 |
|---|---|---|---|---|---|---|
1241204 | The isotope 121sb makes up 57.21% of naturally occurring antimony. The only other naturally occurring isotope is 123sb. Deduce the relative atomic mass of antimony according to this data. How do I do that? | 121.86 | Float | Chemistry | Senior High School | 148,638 |
1618780 | What is the pH of a 0.159 M methylamine solution? {eq}(K_b = 4.4 \times 10^{-4})
{/eq} | 11.91 | Float | Chemistry | Senior High School | 34,507 |
1680132 | How many atoms are in 41.64 grams of lithium? | 3.613e+24 atoms | Float | Chemistry | Senior High School | 68,024 |
889304 | Strontium-90 has a half-life of 28 years. If a 1.00-mg sample was stored for 112 years, what mass of Sr-90 would remain? | 25 mg Sr-90 | Float | Chemistry | Senior High School | 155,242 |
1717590 | In a coffee-cup calorimeter, 1.90 g of {eq}KOH
{/eq} is added to 125 mL of 0.80 M {eq}HCl
{/eq}. The following reaction occurs.
{eq}KOH(s) + HCl(aq) \to H_2O(l) + KCl(aq)
{/eq}
Due to the reaction, the temperature of the solution changes from 30.0 degrees Celsius to 37.2 degrees Celsius. Given that the density of ... | 110.647 kJ/mol | Float | Chemistry | Senior High School | 201,867 |
1082346 | It takes 4 h 39 min for a 2.00-mg sample of radium-230 to decay to 0.25 mg.
What is the half-life of radium-230?
Express your answer using two significant figures.
t_1/2 = | 93 minutes | Integer | Chemistry | Senior High School | 136,423 |
1147747 | Nitric acid is produced from nitrogen monoxide, {eq}\rm
NO
{/eq}, which in turn is prepared from ammonia by the Ostwald process:
{eq}\rm
4NH_3(g) + 5O_2(g) \to 4NO(g) + 6H_2O(g)
{/eq}
What volume of oxygen at {eq}\rm
35 ^\circ C
{/eq} and 2.15 atm is needed to produce 100.0 g of nitrogen monoxide? | 48.6 L | Float | Chemistry | Senior High School | 118,996 |
26187 | After 53.0 min, 43.0% of a compound has decomposed. What is the half-life of this reaction assuming first-order kinetics? | 65.4 min | Float | Chemistry | Senior High School | 114,566 |
1670199 | Calculate the solubility of strontium fluoride, {eq}SrF_2
{/eq}, in pure water. {eq}K_{sp}=2.6 \times 10^{-9}
{/eq}
(a) {eq}1.4 \times 10^{-3}
{/eq} M
(b) {eq}3.4 \times 10^{-4}
{/eq} M
(c) {eq}8.7 \times 10^{-4}
{/eq} M
(d) {eq}5.1 \times 10^{-5}
{/eq} M
(e) {eq}< 1.0 \times 10^{-5}
{/eq} M | c | Multiple Choice | Chemistry | Senior High School | 165,092 |
91039 | Suppose 15.00 grams of {eq}Fe(NO_3)_3
{/eq} reacts with 5.00 grams of {eq}HCl
{/eq} to make {eq}FeCl_3
{/eq} and {eq}HNO_3
{/eq}. How many grams of {eq}FeCl_3
{/eq} can be produced? | 7.41 g | Float | Chemistry | Senior High School | 130,144 |
345386 | Thallium consists of 29.5% TI-203 and 70.5% TI-205. What is the relative atomic mass of thallium? | 204.4 | Float | Chemistry | Senior High School | 154,908 |
378752 | A 1.60 x 10{eq}^{2}{/eq} L kiln is used for vitrifying ceramics. It is currently operating at 1235 degree C , and the pressure is 1.075 atm. How many moles of air molecules are within the confines of the kiln? Express to THREE significant figures. | 1.40 mol | Float | Chemistry | Senior High School | 219,750 |
174249 | The normal boiling point of {eq}C_2H_5OH
{/eq}, is 78.3 degree C and its molar enthalpy of vaporization is 38.56 kJ/mol. What is the change in entropy in the system when {eq}C_2H_5OH
{/eq}(g) at 1 atm condenses to a liquid at the normal boiling point? | 109.8 J/K | Float | Chemistry | University | 25,455 |
1076000 | What is the molar mass of acetic acid (#CH_3COOH#)? | 60.05 g/mol | Float | Chemistry | Senior High School | 118,615 |
1051709 | Which of the following acids (listed with Ka values) and their conjugate base would form a buffer with a pH of 2.34?
a. {eq}HC_{7}H_{5}O_{2}
{/eq}, Ka = 6.5 x 10{eq}^{-5}
{/eq}
b. {eq}HF
{/eq}, Ka = 3.5 x 10{eq}^{-4}
{/eq}
c. {eq}HClO
{/eq}, Ka = 2.9 x 10{eq}^{-8}
{/eq}
d. {eq}HCN
{/eq}, Ka = 4.9 x 10{eq}^{-... | e | Multiple Choice | Chemistry | University | 15,123 |
573275 | How many moles of potassium nitrate is necessary to prepare 116.4 grams of lead(II) nitrate?
{eq}Pb(NO_3)_2(aq) + 2KI(aq) \to PbI_2(s) + 2KNO_3(aq)
{/eq} | 0.5757 mol | Float | Chemistry | Senior High School | 124,624 |
1450044 | How many atoms are there in 14 moles of Cesium Sulfide? | 8.4308*10^24 atoms | Float | Chemistry | Senior High School | 34,913 |
1383840 | Which of the following terms define(s) an acid according to the Bronsted-Lowry theory?
A. proton donor
B. proton acceptor
C. electron-pair donor
D. electron pair acceptor
E. H1+ donor
F. H1+ acceptor
G. OH1- donor
H. OH1- acceptor | A | Multiple Choice | Chemistry | Senior High School | 197,706 |
1837531 | A chemist runs a chemical reaction at 25^{o} C and decides that it proceeds far too rapidly. As a result he decides that the reaction rate must be decreased by a factor of 4. At what temperature should the chemist run the reaction to achieve this goal? | T_2 = \dfrac{1}{\dfrac{1}{T_1} - \dfrac{R\ln(0.25)}{E_a}} | Expression | Chemistry | University | 79,293 |
865607 | Explain and derive R in an Ideal gas Equation. | R = PV/nT | Expression | Chemistry | Senior High School | 211,126 |
1366386 | Balance the following equation.
{eq}Mg+Mn_2O_3 \rightarrow MgO+MnO
{/eq} | Mg+Mn_2O_3 -> MgO+2MnO | Expression | Chemistry | Senior High School | 130,975 |
599230 | The mass of P4 O10 that will be obtained from the reaction of 1.33 grams of P4 and 5.07 grams of oxygen is what? | 3.04 g | Float | Chemistry | Senior High School | 134,582 |
2074896 | List the following radicals in order of decreasing stability (i.e., from most stable to least stable).To rank items as equivalent, overlap them.
(CH3)3C-, CH2=CHCH2-, CH3CH2-, CH3-, (CH3)2CH- | CH2=CHCH2- > (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3- | List | Chemistry | Senior High School | 66,242 |
1884779 | If 15.0g of KCl is added to 100.0g of water at {eq}30.0^oC{/eq}, how much more must be added to saturate the solution? | 22.2 grams | Float | Chemistry | Senior High School | 194,511 |
991049 | At STP, what is the density of {eq}\displaystyle
SO_2(g)?
{/eq} | 2.86 g/L | Float | Chemistry | Senior High School | 166,623 |
450148 | How much carbon dioxide is released when a #1*L# volume of octane is combusted? | 49 mol | Integer | Chemistry | Senior High School | 158,028 |
2080019 | Cyclopropane ({eq}C_3H_6
{/eq}) reacts to form propene ({eq}C_3H_6
{/eq}) in the gas phase. The reaction is first order in cyclopropane and has a rate constant of {eq}5.87 \times 10^{-4}
{/eq} /s at 485 {eq}^{\circ}
{/eq}C. If a 2.5 L reaction vessel initially contains 722 torr of cyclopropane at 485 {eq}^{\circ}
... | 3368 seconds | Integer | Chemistry | Senior High School | 32,554 |
851976 | If the pH of a saturated solution of a metal(II) hydroxide, {eq}M(OH)_2
{/eq}, is 9.3, what is the solubility product constant, {eq}K_{sp}
{/eq}? | 4.0e-15 | Float | Chemistry | Senior High School | 78,632 |
1206351 | In the natural world, calcium carbonate {eq}(CaCO_3)
{/eq} is the salt that dissolves in water to make it alkaline. Using the following chemical equation for the dissolving of sodium carbonate as a reference, write the balanced chemical equation for the dissolving of calcium carbonate {eq}(CaCO_3)
{/eq}.
{eq}Na_2CO_... | CaCO_3 + 2H_2O -> Ca^{2+} + 2OH^- + H_2CO_3 | Expression | Chemistry | Senior High School | 74,393 |
2037193 | What volume (to the nearest {eq}0.1 \ mL
{/eq}) of {eq}5.20 \ M \ NaOH
{/eq} must be added to {eq}0.750 \ L
{/eq} of {eq}0.300 \ M \ HNO_2
{/eq} to prepare a {eq}pH = 4.20
{/eq} buffer? | 37.9 mL | Float | Chemistry | University | 147,385 |
1499047 | When sulfuric acid reacts with ammonia solution, an ammonium salt is produced.
Calculate the mass of ammonia salt that would remain if the solution were evaporated to dryness. | Mass_(NH4)2SO4= (mass_NH3/17g/mol) * (1mol_(NH4)2SO4/1mol_NH3) * 132g/mol | Expression | Chemistry | Senior High School | 179,258 |
1367080 | A 58.5 L constant-volume cylinder containing 1.97 moles of Xe is heated until the pressure reaches 3.11 atm. What is the final temperature in degrees Celsius (C)? | 851.88 °C | Float | Chemistry | Senior High School | 154,972 |
576966 | What volume does 35 moles of N{eq}_{2}
{/eq} occupy at STP? | 784 L | Integer | Chemistry | Senior High School | 165,995 |
734867 | Draw the structure of {eq}\displaystyle \rm Sodium \ 3-mercapto-2-oxopentanoate
{/eq}. | /cimages/multimages/16/merca6069589883133809631.jpg | Other | Chemistry | Senior High School | 67,683 |
1399940 | Calculate the mass in kilograms of sucrose ({eq}C_{12}H_{22}O_{11}
{/eq}) in a 565 mL sample of a 8.91 M sucrose solution. | 1.72 kg | Float | Chemistry | Senior High School | 68,081 |
1582362 | Consider the reversible, isothermal, constant-pressure freezing of 1 mole of water at 0 degrees Celsius and 1 atm. Calculate {eq}\Delta H
{/eq}. | 6.01 kJ | Float | Chemistry | University | 75,451 |
857223 | Draw the structure given the IUPAC name trans-4-fluorocyclohexan-1-ol. | <img>/cimages/multimages/16/acyloch2481649252451357932.png</img> | Other | Chemistry | Senior High School | 124,755 |
1554174 | An elemental gas has a mass of 10.3 g. If the volume is 58.4 L and the pressure is 101 kPa at a temperature of 2.5 C, what is the gas? | helium | String | Chemistry | Senior High School | 120,464 |
2031251 | Which of the following molecules has polar bonds but is a non polar molecule?
(a) {eq}BF_3
{/eq}
(b) {eq}CCL_4
{/eq}
(c) {eq}CO
{/eq}
(d) {eq}SF_4
{/eq} | b | Multiple Choice | Chemistry | Senior High School | 110,603 |
561669 | Decaborane, {eq}\displaystyle \rm
{/eq}, was used as a fuel for rockets in the 1950s. It ignites spontaneously with {eq}\displaystyle \rm O_2
{/eq} according to the following reaction:
{eq}\displaystyle \rm B_{10}H_{14} + 11O_2 \to 5B_2O_3 + 7H_2O
{/eq}
If the total mass of both components in a decaborane/oxygen r... | 1.45e6 g | Float | Chemistry | Senior High School | 69,499 |
1205726 | What is the volume of oxygen (measured at room temperature and pressure) required for the complete combustion of 10 moles of octane?
{eq}2C_8H_{18} + 25O_2 \to 16CO_2 + 18H_2O
{/eq} | 3058.225 L | Float | Chemistry | Senior High School | 77,377 |
1510581 | How many molecules (not moles) of NH3 are produced from 8.21 * 10{eq}^{-4}
{/eq} g of H2 ? Express your answer numerically as the number of molecules. | 2.71e-4 mol | Float | Chemistry | Senior High School | 52,212 |
493524 | Calculate the pH of 0.35 mole per liter solution of butanoic acid? | 2.64 | Float | Chemistry | Senior High School | 97,298 |
1933007 | How many grams of which reactant remains after the reaction of 15.0 g of MnO{eq}_2
{/eq} (86.9 g/mol) and 30.0 g of HCl (FW = 36.5 g/mol) according to the following chemical equation?
MnO{eq}_2
{/eq}(s) + 4HCl(aq) | 4.891 g of HCl | Float | Chemistry | Senior High School | 121,269 |
1909811 | Automobile airbags contain solid sodium azide, {eq}NaN_3
{/eq}, that reacts to produce nitrogen gas when heated, thus inflating the bag. Calculate the value of {eq}w
{/eq} (work) for the following system if 11.8 g of {eq}NaN_3
{/eq} reacts completely at 1.00 atm and 22 {eq}^{\circ}
{/eq}C. | -662.6 J | Float | Chemistry | Senior High School | 157,648 |
1941964 | To which substance is dilute sulfuric acid added to prepare lead(II) sulfate? | Any soluble lead(II) salt | String | Chemistry | Senior High School | 215,169 |
851260 | Identify the steps required to standardize a 0.1M HCl stock solution with sodium carbonate:
{eq}Na_2CO_3
{/eq}, mol wt. = 105.99 g/mol. | 1. Dry the sodium carbonate. 2. Weigh ~0.001 mol of sodium carbonate and dissolve in ~25 mL of water. 3. Add phenolphthalein indicator and titrate with HCl until the pink color disappears. Record the volume. 4. Add methyl orange indicator and titrate with HCl until the solution turns red. Record the volume. 5. Calcula... | List | Chemistry | University | 29,413 |
1339371 | An important industrial process for synthesizing the ammonia used in agricultural fertilizers involves the combination of {eq}\rm
N_2
{/eq} and {eq}\rm
H_2
{/eq}:
{eq}\rm
N_2 (g) + 3 H_2 (g) \rightleftharpoons 2NH_3 (g)\ K_C = 3.552 \times 10^8\ \text{at}\ 63.86 ^\circ C.
{/eq}
What is the value of {eq}\rm
K_p... | 4.639e5 | Float | Chemistry | Senior High School | 194,008 |
1643784 | Suppose 0.0139g of {eq}HNO_3
{/eq} is dissolved in 625 mL of an aqueous solution. what is the pH? | 3.452 | Float | Chemistry | Senior High School | 204,277 |
413316 | What is the #"pH"# of a #"1.5-M"# solution of ammonia? The dissociation constant of ammonia at #25.0^@"C"# is #1.80 * 10^-5#. | 11.72 | Float | Chemistry | Senior High School | 207,113 |
1051023 | 9.45 grams of liquid hexane ({eq}C_6H_{14}
{/eq}) is introduced into a 10.0-L vessel containing 13.15 atm of oxygen gas at 21 degrees Celsius and ignited, yielding carbon dioxide and water. If the vessel is then cooled to -10 degrees Celsius, what will be the gas pressure inside the vessel? | 10.91 atm | Float | Chemistry | Senior High School | 89,045 |
1509344 | A {eq}\displaystyle \rm 20.0 \ mL
{/eq} sample of {eq}\displaystyle \rm 0.0200 \ M \ Cu^{2+}
{/eq} buffered at {eq}\displaystyle \rm pH
{/eq} is titrated with {eq}\displaystyle \rm 0.0200 \ M
{/eq} EDTA. Calculate the {eq}\displaystyle \rm pCu^{2+}
{/eq} at {eq}\displaystyle \rm 20.0 \ mL
{/eq}. | 1.69 | Float | Chemistry | University | 42,631 |
962464 | The molar heat of vaporization of carbon disulfide (CS2) is 28.4 kJ/mol at its normal boiling point of 46 C. How much energy (heat) is required to vaporize 2 g of CS2 at 46 C? Answer in units of Joules. | 700 J | Integer | Chemistry | Senior High School | 42,704 |
795028 | What is the oxidation number of oxygen in #OF_2(g)#? | +2 | Integer | Chemistry | Senior High School | 168,526 |
621433 | Which is equal to the pKa of a weak acid?
a) the equilibrium concentration of conjugate base
b) the pKa of its conjugate acid
c) the pH of a solution containing equal amounts of the weak base
d) its relative molecular mass | C | Multiple Choice | Chemistry | University | 30,120 |
1463238 | Calculate the {eq}pH
{/eq} of a buffer that is {eq}0.255 \ M
{/eq} in {eq}NaHCO_3
{/eq} and {eq}0.280 \ M
{/eq} in {eq}Na_2CO_3
{/eq} . Express your answer using two decimal places. | 10.37 | Float | Chemistry | University | 194,651 |
70904 | Calculate the amount of water required to reduce the temperature of the following sample of metal. Assume that you can use as much water (at 4 degrees C) as required.
A cube of 25 lb of aluminum, from 700 degrees F to 38 degrees F. | 1,260 kg | Float | Chemistry | Senior High School | 49,381 |
676616 | The half-life of iodine-131 is 8.02 days. How long would it take for 10% of a sample to decay in hours? | 29 hours | Integer | Chemistry | Senior High School | 150,347 |
1348353 | At 18 degrees Celsius, {eq}K_p = 1 \times 10^{-31}
{/eq} for the following reaction.
{eq}N_2(g) + O_2(g) \leftrightharpoons 2NO(g)
{/eq}
Calculate the concentration of {eq}NO
{/eq} in molecules/cm{eq}^3
{/eq} that can exist in equilibrium in air at 18 degrees Celsius. In air, {eq}P_{N_2}
{/eq} = 0.8 atm and {eq}... | 3188.3479 molecules/cm^3 | Float | Chemistry | University | 120,911 |
1061337 | The rock in a particular iron ore deposit contains {eq}\rm 84 \%\ Fe_2O_3
{/eq} by mass. How many kilograms of the rock must be processed to obtain {eq}1100\ kg
{/eq} of iron? | 1872.3 kg | Float | Chemistry | Senior High School | 1,522 |
807729 | If 5.31 moles of an ideal gas has a pressure of 5.11 atm, and a volume of 39.85 L what is the temperature of the sample? | 467.102 | Float | Chemistry | Senior High School | 181,655 |
42647 | Complete and balance the following acid/base reaction.
{eq}HCO_2H(aq) + H_2O(l) \to
{/eq} | HCO_2^-(aq) + H_3O^+(aq) | Expression | Chemistry | Senior High School | 192,657 |
520508 | Calculate the {eq}\displaystyle \rm pH
{/eq} of the case in the titration of {eq}\displaystyle \rm 35.0 \ mL
{/eq} of {eq}\displaystyle \rm 0.240 \ M \ NaOH (aq)
{/eq}, with {eq}\displaystyle \rm 0.24 \ M \ HBr (aq)
{/eq} after the addition of {eq}\displaystyle \rm 50 \ mL
{/eq} of {eq}\displaystyle \rm HBr
{/eq}... | 1.38 | Float | Chemistry | Senior High School | 18,648 |
1377520 | Calculate the minimum concentration of 100.0 m L of sodium sulfate that is required to form a precipitate with 100.0 m L of 1.00 * 10{eq}^{-2}
{/eq} M calcium nitrate. | 0.0197 M | Float | Chemistry | Senior High School | 227,925 |
271963 | Draw the structure of 3,3-dimethylcyclopentene. | <img>/cimages/multimages/16/33-dimethylcyclopentene_structural_formula6738665594770645387.png</img> | Other | Chemistry | Senior High School | 66,026 |
1374399 | What is the rate law of {eq}S_2O_8^{2-} + 3I^- \to 2SO_4^{2-} + I_3^-?
{/eq} | Rate=k[S_2O_8^{2-}][I^-]^3 | Expression | Chemistry | University | 68,771 |
1013956 | What is the total number of nitrogen atoms in 0.25 mole of #NO_2# gas? | 1.5 x 10^23 | Float | Chemistry | Senior High School | 27,134 |
433017 | What is the mass of {eq}\rm S_2Cl_2
{/eq}, if {eq}342
{/eq} grams of {eq}\rm S
{/eq} is reacted with an excess of {eq}\rm Cl_2
{/eq}? | 720.2g | Float | Chemistry | Senior High School | 39,772 |
269398 | If you place 10 L of propanol {eq}\rm (C_3H_8O)
{/eq} in a sealed room that is 7.5 m long, 3 m wide and 3 m high, will all the propanol eveporate?If some liquid remains, how much will there be the vapor pressure of propanol is {eq}\rm 10.7\ torr
{/eq} at {eq}25 ^\circ C
{/eq}, and the density if the liquid at this t... | 7L | Integer | Chemistry | University | 126,892 |
1122626 | . Use arrows to show electron pairing in the 4s and 3d orbitals of the following:
Nickel | 4s: ↑↓
3d: ↑↓ ↑↓ ↑↓ ↑ ↑ | List | Chemistry | Senior High School | 95,430 |
911218 | For the titration of 50.0 mL of 0.230 M HClO(aq) with 0.230 M KOH(aq), calculate the pH after the addition of 25.0 mL of KOH. | 7.46 | Float | Chemistry | Senior High School | 146,377 |
84906 | The mineral crocidolite has the formula {eq}Na_2Fe_5(Si_4O_{11})_2(OH)_2
{/eq}. How many of the iron ions per formula unit are in the 2 oxidation state and how many are in the 3 oxidation state? | 3 iron atoms have a +2 oxidation state, and 2 iron atoms have a +3 oxidation state | List | Chemistry | Senior High School | 36,283 |
1431427 | What is the molarity of an HCl solution if 6 00 mL HCl solution is titrated with 24 6 mL of 0 165 M NaOH solution?
HCl(aq) + NaOH(aq) --> NaCl(aq) + H_2O(l)
molarity = | 0.676 M | Float | Chemistry | Senior High School | 50,929 |
1762932 | A compound contains 83.24% by mass carbon. Calculate the molar mass of the compound if it contains 5 moles of carbon per mole of compound. | 72.140 g/mol | Float | Chemistry | Senior High School | 186,505 |
1621592 | What is the chemical equation for the first ionization step of carbonic acid? | H2CO3 (aq) + H2O (l) ⇌ HCO3- (aq) + H3O+ (aq) | Expression | Chemistry | Senior High School | 67,903 |
614454 | Calculate the radius of iridium atom, given that {eq}\text{Ir}
{/eq} has an FFC crystal structure, a density of 22.4 {eq}g/cm^3
{/eq} and an atomic weight of 192.2 {eq}g/mol
{/eq}. | 135.7 pm | Float | Chemistry | University | 36,146 |
1503339 | If the pH of a 0.45 M weak acid is measured to be 4.32, what is its {eq}K_a
{/eq} value? | 5.1e-9 | Float | Chemistry | Senior High School | 113,753 |
1837634 | How many grams of HI should be added to 265 mL of 0.215 M HCI so that the resulting solution has a pH of 0.38? Assume that the addition of HI does not change the volume of the resulting solution. | 6.91 g | Float | Chemistry | Senior High School | 36,532 |
715754 | Find the pH of the following solution of mixture of acids.
{eq}\rm
0.125\ M
{/eq} in {eq}\rm
HBr
{/eq} and {eq}\rm
0.130\ M
{/eq} in {eq}\rm
HCHO_2
{/eq}
Express your answer is three decimal places. | 0.903 | Float | Chemistry | Senior High School | 131,121 |
1580229 | Find the density of {eq}\rm CO_2 (g)
{/eq} at {eq}25 ^\circ C
{/eq} and {eq}715\ \rm torr
{/eq}. | 1.69 g/L | Float | Chemistry | Senior High School | 125,005 |
2029687 | What is the number of waves made by an electron moving in an orbit with maximum magnetic quantum number +3? | 4 | Integer | Chemistry | Senior High School | 101,842 |
615073 | A buffer solution was prepared by mixing #"392 mL"# of #"0.301 M"# #"NaClO"# and #"181 mL"# of #"0.281 M"# #"HClO"#. Calculate the #"pH"# of the solution? | 7.860 | Float | Chemistry | University | 23,461 |
1674237 | Calculate the % (m/m) of argon gas in a mixture containing 55.0 g of argon gas and 90.0 g of helium gas. | 37.93% | Percentage | Chemistry | Senior High School | 135,267 |
769798 | Calculate the concentrations of all species present in a 0.63 M {eq}NH_3
{/eq} solution. {eq}(K_b = 1.8 \times 10^{-5})
{/eq} | [NH_4^+] = [OH^-] = 0.00336 M, [NH_3] = 0.60M, [H^+] = 3.0e-12M | List | Chemistry | Senior High School | 63,981 |
355314 | After 67.0 minutes, 32.0{eq}\%
{/eq} of a compound has decomposed. What is the half-life of this reaction assuming first order kinetics? | 120.42 min | Float | Chemistry | Senior High School | 179,964 |
502294 | Write the electron configuration for the below element by using the symbol of the previous noble gas to indicate the core electrons.
titanium, Z = 22. | [Ar] 4s^2 3d^2 | String | Chemistry | Senior High School | 214,506 |
105619 | Calculate the mass of NaCl in a 37-mL sample of a 1.4 M NaCl solution. | 3.0 grams | Float | Chemistry | Senior High School | 106,789 |
1825748 | What is the mole ratio of sodium acetate to acetic acid in a buffer with a pH of 5.75? (Ka of acetic acid = 1.8 x 10{eq}^{-5}
{/eq}) . | 10.1 | Float | Chemistry | Senior High School | 50,779 |
584359 | A certain reaction has an activation energy of 69.0 kJ/mol and a frequency factor of {eq}A_1 = 6.60 \times 10^{12}
{/eq} M{eq}^{-1} \cdot
{/eq}s{eq}^{-1}
{/eq}. What is the rate constant, {eq}k
{/eq}, of this reaction at 23.0 degrees Celsius? | 4.46 M^{-1} s^{-1} | Float | Chemistry | University | 27,518 |
380567 | Predict the ideal values for the bond angles about the highlighted carbon atom: CH{eq}_3
{/eq}C{eq}\underline{C}
{/eq}CH{eq}_2
{/eq}COOH. | 180 degrees | Integer | Chemistry | Senior High School | 85,737 |
2097910 | What is the mass (in grams) of {eq}9.10 \times 10^{24}
{/eq} molecules of methanol ({eq}CH_3OH
{/eq})? | 484.124 g | Float | Chemistry | Senior High School | 136,067 |
226000 | If 100 mL of 0.03 M {eq}HCl
{/eq} solution is added to 100 mL of buffer solution which is 0.1 M in {eq}NH_3
{/eq}, and 0.1 M in {eq}NH_4Cl
{/eq}, what will be the pH of the new solution? | 9 | Integer | Chemistry | Senior High School | 51,839 |
620753 | How many moles of oxygen are needed to completely react with 9.5 g of sodium | 0.10325 moles of O₂ | Float | Chemistry | Senior High School | 82,149 |
1911275 | A chemistry student is given 500 mL of a 0.90 M ammonia solution. Ammonia is a weak base with {eq}K_b = 1.8 \times 10^{-5}
{/eq}. What mass of {eq}NH_4Cl
{/eq} should the student dissolve in the {eq}NH_3
{/eq} solution to turn it into a buffer with pH = 9.71? | 8.4 g | Float | Chemistry | University | 139,543 |
1730743 | How many diastereomers can #H_3C-CH=CH-CH(OH)CH_3# generate? | 4 | Integer | Chemistry | Senior High School | 100,664 |
616451 | Calculate the pH that would result if 25.0 ml of 0.200 M HNO_3 is added to 20.0 ml of 0.250 M KOH. | 7.00 | Float | Chemistry | Senior High School | 193,893 |
159321 | What is the complete ground state electron configuration for the zinc atom? | 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 | String | Chemistry | Senior High School | 9,240 |
1968161 | $$C_3H_8 + O_2 \rightleftharpoons CO_2 +H_2O
$$
Starting with 37.78 g of propane, how much water will be produced? | 66.2 g | Float | Chemistry | Senior High School | 206,243 |
472666 | {eq}\displaystyle A \longrightarrow P
{/eq} is a first order reaction and has at {eq}\displaystyle t_{\frac {1} {2}}
{/eq} of {eq}20.38
{/eq} minutes, if during an experiment the concentration of {eq}A
{/eq} is {eq}0.5\ M
{/eq} at {eq}1
{/eq} hour time point, what would be the initial concentration of {eq}... | 3.8 M | Float | Chemistry | Senior High School | 180,944 |
25205 | A 27.0 mL solution of 0.100 M CH{eq}_3
{/eq}COOH is titrated with a 0.200 M KOH solution. Calculate the pH after the addition of 0.00 mL of the KOH solution. | 2.87 | Float | Chemistry | University | 134,365 |
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