Chapter 14 Key Terms

acid

proton donor

acid ionization

reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid

acid ionization constant (K_a)

equilibrium constant for an acid ionization reaction

acid-base indicator

weak acid or base whose conjugate partner imparts a different solution color; used in visual assessments of solution pH

acid-base reaction

reaction involving the transfer of a hydrogen ion between reactant species

acidic

a solution in which [H₃O⁺] > [OH⁻]

amphiprotic

species that may either donate or accept a proton in a Bronsted-Lowry acid-base reaction

amphoteric

species that can act as either an acid or a base

autoionization

reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions

base

proton acceptor

base ionization

reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base

base ionization constant (K_b)

equilibrium constant for a base ionization reaction

basic

a solution in which [H₃O⁺] < [OH⁻]

Brønsted-Lowry acid

proton donor

Brønsted-Lowry base

proton acceptor

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

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)

color-change interval

range in pH over which the color change of an indicator is observed

conjugate acid

substance formed when a base gains a proton

conjugate base

substance formed when an acid loses a proton

diprotic acid

acid containing two ionizable hydrogen atoms per molecule

diprotic base

base capable of accepting two protons

Henderson-Hasselbalch equation

logarithmic version of the acid ionization constant expression, conveniently formatted for calculating the pH of buffer solutions

ion-product constant for water (K_w)

equilibrium constant for the autoionization of water

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)

monoprotic acid

acid containing one ionizable hydrogen atom per molecule

neutral

describes a solution in which [H₃O⁺] = [OH⁻]

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

percent ionization

ratio of the concentration of ionized acid to initial acid concentration expressed as a percentage

pH

logarithmic measure of the concentration of hydronium ions in a solution

pOH

logarithmic measure of the concentration of hydroxide ions in a solution

stepwise ionization

process in which a polyprotic acid is ionized by losing protons sequentially

strong acid

acid that reacts completely when dissolved in water to yield hydronium ions

strong base

base that reacts completely when dissolved in water to yield hydroxide ions

titration curve

plot of some sample property (such as pH) versus volume of added titrant

triprotic acid

acid that contains three ionizable hydrogen atoms per molecule

weak acid

acid that reacts only to a slight extent when dissolved in water to yield hydronium ions

weak base

base that reacts only to a slight extent when dissolved in water to yield hydroxide ions