text
stringlengths
2
2.33k
source
stringclasses
826 values
Systems at equilibrium can be disturbed by changes to temperature, concentration, and, in some cases, volume and pressure. The system’s response to these disturbances is described by Le Châtelier’s principle: An equilibrium system subjected to a disturbance will shift in a way that counters the disturbance and re-...
https://openstax.org/books/chemistry-atoms-first-2e/pages/13-summary
Calculating values for equilibrium constants and/or equilibrium concentrations is of practical benefit to many applications. A mathematical strategy that uses initial concentrations, changes in concentrations, and equilibrium concentrations (and goes by the acronym ICE) is useful for several types of equilibrium calcul...
https://openstax.org/books/chemistry-atoms-first-2e/pages/13-summary
K w = [H 3 O + ][OH − ] = 1.0 × × 10 −14 (at 25 °C)
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
pH = −log [ H 3 O + ] pH = −log [ H 3 O + ]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
pOH = −log[OH − ]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
[H 3 O + ] = 10 −pH
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
[OH − ] = 10 −pOH
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
pH + pOH = p K w = 14.00 at 25 °C
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
K a = [ H 3 O + ] [ A − ] [ HA ] K a = [ H 3 O + ] [ A − ] [ HA ]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
K b = [ HB + ] [ OH − ] [ B ] K b = [ HB + ] [ OH − ] [ B ]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
K a × × K b = 1.0 × × 10 −14 = K w
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
Percent ionization = [ H 3 O + ] eq [ HA] 0 × 100 Percent ionization = [ H 3 O + ] eq [ HA] 0 × 100
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
p K a = −log K a
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
p K b = −log K b
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
pH = p K a + log [ A − ] [ HA ] pH = p K a + log [ A − ] [ HA ]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-equations
acid ionization : reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
acid ionization constant (Ka) : equilibrium constant for an acid ionization reaction
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
acid-base indicator : weak acid or base whose conjugate partner imparts a different solution color; used in visual assessments of solution pH
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
acidic : a solution in which [H3O+] > [OH−]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
amphiprotic : species that may either donate or accept a proton in a Bronsted-Lowry acid-base reaction
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
amphoteric : species that can act as either an acid or a base
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
autoionization : reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
base ionization : reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
base ionization constant (Kb) : equilibrium constant for a base ionization reaction
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
basic : a solution in which [H3O+] < [OH−]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
Brønsted-Lowry acid : proton donor
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
Brønsted-Lowry base : proton acceptor
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
buffer : mixture of appreciable amounts of a weak acid-base pair. The pH of a buffer resists change when small amounts of acid or base are added
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
buffer capacity : amount of an acid or base that can be added to a volume of a buffer solution before its pH changes significantly (usually by one pH unit)
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
color-change interval : range in pH over which the color change of an indicator is observed
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
conjugate acid : substance formed when a base gains a proton
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
conjugate base : substance formed when an acid loses a proton
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
diprotic acid : acid containing two ionizable hydrogen atoms per molecule
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
diprotic base : base capable of accepting two protons
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
Henderson-Hasselbalch equation : logarithmic version of the acid ionization constant expression, conveniently formatted for calculating the pH of buffer solutions
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
ion-product constant for water (Kw) : equilibrium constant for the autoionization of water
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
leveling effect : observation that acid-base strength of solutes in a given solvent is limited to that of the solvent’s characteristic acid and base species (in water, hydronium and hydroxide ions, respectively)
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
monoprotic acid : acid containing one ionizable hydrogen atom per molecule
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
neutral : describes a solution in which [H3O+] = [OH−]
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
oxyacid : ternary compound with acidic properties, molecules of which contain a central nonmetallic atom bonded to one or more O atoms, at least one of which is bonded to an ionizable H atom
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
percent ionization : ratio of the concentration of ionized acid to initial acid concentration expressed as a percentage
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
pH : logarithmic measure of the concentration of hydronium ions in a solution
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
pOH : logarithmic measure of the concentration of hydroxide ions in a solution
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
stepwise ionization : process in which a polyprotic acid is ionized by losing protons sequentially
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
titration curve : plot of some sample property (such as pH) versus volume of added titrant
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
triprotic acid : acid that contains three ionizable hydrogen atoms per molecule
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-key-terms
A compound that can donate a proton (a hydrogen ion) to another compound is called a Brønsted-Lowry acid. The compound that accepts the proton is called a Brønsted-Lowry base. The species remaining after a Brønsted-Lowry acid has lost a proton is the conjugate base of the acid. The species formed when a Brønsted-Lo...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
The ion product of water,Kwis the equilibrium constant for the autoionization reaction:
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
Concentrations of hydronium and hydroxide ions in aqueous media are often represented as logarithmic pH and pOH values, respectively. At 25 °C, the autoprotolysis equilibrium for water requires the sum of pH and pOH to equal 14 for any aqueous solution. The relative concentrations of hydronium and hydroxide ion in a s...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
The relative strengths of acids and bases are reflected in the magnitudes of their ionization constants; the stronger the acid or base, the larger its ionization constant. A reciprocal relation exists between the strengths of a conjugate acid-base pair: the stronger the acid, the weaker its conjugate base. Water exerts...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
The ions composing salts may possess acidic or basic character, ionizing when dissolved in water to yield acidic or basic solutions. Acidic cations are typically the conjugate partners of weak bases, and basic anions are the conjugate partners of weak acids. Many metal ions bond to water molecules when dissolved to yie...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
An acid that contains more than one ionizable proton is a polyprotic acid. These acids undergo stepwise ionization reactions involving the transfer of single protons. The ionization constants for polyprotic acids decrease with each subsequent step; these decreases typically are large enough to permit simple equilibrium...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
Solutions that contain appreciable amounts of a weak conjugate acid-base pair are called buffers. A buffered solution will experience only slight changes in pH when small amounts of acid or base are added. Addition of large amounts of acid or base can exceed the buffer capacity, consuming most of one conjugate partner ...
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
The titration curve for an acid-base titration is typically a plot of pH versus volume of added titrant. These curves are useful in selecting appropriate acid-base indicators that will permit accurate determinations of titration end points.
https://openstax.org/books/chemistry-atoms-first-2e/pages/14-summary
M p X q ( s ) ⇌ p M m+ ( a q ) + q X n− ( a q ) K sp = [ M m+ ] p [ X n− ] q M p X q ( s ) ⇌ p M m+ ( a q ) + q X n− ( a q ) K sp = [ M m+ ] p [ X n− ] q
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-equations
common ion effect : effect on equilibrium when a substance with an ion in common with the dissolved species is added to the solution; causes a decrease in the solubility of an ionic species, or a decrease in the ionization of a weak acid or base
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
complex ion : ion consisting of a central atom surrounding molecules or ions called ligands via coordinate covalent bonds
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
coordinate covalent bond : (also, dative bond) covalent bond in which both electrons originated from the same atom
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
coupled equilibria : system characterized the simultaneous establishment of two or more equilibrium reactions sharing one or more reactant or product
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
dissociation constant : (Kd) equilibrium constant for the decomposition of a complex ion into its components
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
formation constant : (Kf) (also, stability constant) equilibrium constant for the formation of a complex ion from its components
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
Lewis acid : any species that can accept a pair of electrons and form a coordinate covalent bond
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
Lewis acid-base adduct : compound or ion that contains a coordinate covalent bond between a Lewis acid and a Lewis base
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
Lewis acid-base chemistry : reactions involving the formation of coordinate covalent bonds
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
Lewis base : any species that can donate a pair of electrons and form a coordinate covalent bond
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
ligand : molecule or ion acting as a Lewis base in complex ion formation; bonds to the central atom of the complex
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
molar solubility : solubility of a compound expressed in units of moles per liter (mol/L)
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
selective precipitation : process in which ions are separated using differences in their solubility with a given precipitating reagent
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
solubility product constant (Ksp) : equilibrium constant for the dissolution of an ionic compound
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-key-terms
The equilibrium constant for an equilibrium involving the precipitation or dissolution of a slightly soluble ionic solid is called the solubility product,Ksp, of the solid. For a heterogeneous equilibrium involving the slightly soluble solid MpXqand its ions Mm+and Xn–:
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
the solubility product expression is:
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
The solubility product of a slightly soluble electrolyte can be calculated from its solubility; conversely, its solubility can be calculated from itsKsp, provided the only significant reaction that occurs when the solid dissolves is the formation of its ions.
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
A slightly soluble electrolyte begins to precipitate when the magnitude of the reaction quotient for the dissolution reaction exceeds the magnitude of the solubility product. Precipitation continues until the reaction quotient equals the solubility product.
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
A Lewis acid is a species that can accept an electron pair, whereas a Lewis base has an electron pair available for donation to a Lewis acid. Complex ions are examples of Lewis acid-base adducts and comprise central metal atoms or ions acting as Lewis acids bonded to molecules or ions called ligands that act as Lewis b...
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
Systems involving two or more chemical equilibria that share one or more reactant or product are called coupled equilibria. Common examples of coupled equilibria include the increased solubility of some compounds in acidic solutions (coupled dissolution and neutralization equilibria) and in solutions containing ligands...
https://openstax.org/books/chemistry-atoms-first-2e/pages/15-summary
E cell ° = E cathode ° − E anode ° E cell ° = E cathode ° − E anode °
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
E cell ° = R T n F ln K E cell ° = R T n F ln K
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
E cell ° = 0.02 57 V n ln K = 0.0 592 V n log K ( at 298.15 K ) E cell ° = 0.02 57 V n ln K = 0.0 592 V n log K ( at 298.15 K )
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
E cell = E cell ° − R T n F ln Q (Nernst equation) E cell = E cell ° − R T n F ln Q (Nernst equation)
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
E cell = E ° cell − 0.0592 V n log Q ( at 298.15 K ) E cell = E ° cell − 0.0592 V n log Q ( at 298.15 K )
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
Δ G = − nFE cell
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
Δ G ° = − n F E cell ° Δ G ° = − n F E cell °
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
w ele = w max = − n F E cell w ele = w max = − n F E cell
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
Q = I × × t = n × × F
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-equations
active electrode : electrode that participates as a reactant or product in the oxidation-reduction reaction of an electrochemical cell; the mass of an active electrode changes during the oxidation-reduction reaction
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
alkaline battery : primary battery similar to adry cellthat uses an alkaline (often potassium hydroxide) electrolyte; designed to be an improved replacement for the dry cell, but with more energy storage and less electrolyte leakage than typical dry cell
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
anode : electrode in an electrochemical cell at which oxidation occurs
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
battery : single or series of galvanic cells designed for use as a source of electrical power
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
cathode : electrode in an electrochemical cell at which reduction occurs
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
cathodic protection : approach to preventing corrosion of a metal object by connecting it to asacrificial anodecomposed of a more readily oxidized metal
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
cell notation (schematic) : symbolic representation of the components and reactions in an electrochemical cell
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
cell potential (Ecell) : difference in potential of the cathode and anode half-cells
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
concentration cell : galvanic cell comprising half-cells of identical composition but for the concentration of one redox reactant or product
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
corrosion : degradation of metal via a natural electrochemical process
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
dry cell : primary battery, also called a zinc-carbon battery, based on the spontaneous oxidation of zinc by manganese(IV)
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
electrode potential (EX) : the potential of a cell in which the half-cell of interest acts as a cathode when connected to the standard hydrogen electrode
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
electrolysis : process using electrical energy to cause a nonspontaneous process to occur
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
electrolytic cell : electrochemical cell in which an external source of electrical power is used to drive an otherwise nonspontaneous process
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
Faraday’s constant (F) : charge on 1 mol of electrons;F= 96,485 C/mol e−
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms
fuel cell : devices similar to galvanic cells that require a continuous feed of redox reactants; also called aflow battery
https://openstax.org/books/chemistry-atoms-first-2e/pages/16-key-terms