Chapters 17-18 Vocab

Equilibrium constant (K)

The value obtained when equilibrium concentrations are substituted into the reaction quotient.

Haber Process

An industrial process used to form ammonia from its elements.

Law of chemical equilibrium (law of mass action)

The law stating that, when a system reaches equilibrium at a given temperature, the ratio of quantities that make up the reaction quotient has a constant numerical value.

**Le Châtelier’s principle**

A principle stating that, if a system in a state of equilibrium is disturbed, it will undergo a change that shifts its equilibrium position in a direction that reduces the effect of the disturbance.

Metabolic pathway

A biochemical reaction sequence that flows in one direction, with each reaction catalyzed by an enzyme.

Reaction quotient (Q) or mass action expression

A ratio of terms for a given reaction consisting of product concentrations multiplied together and divided by reactant concentrations multiplied together, with each concentration raised to the power of its balancing coefficient. The value of *Q* changes until the system reaches equilibrium, at which point it equals *K.*

Van’t Hoff equation

An equation for calculating the change in equilibrium constant that occurs with a change in temperature

acid-dissociation (acid-ionization) constant (Ka)

An equilibrium constant for the dissociation of an acid (HA) in H2O to yield the conjugate base (A−) and H3O+

Adduct

The product of a Lewis acid-base reaction, a species that contains a new covalent bond.

Amphiprotic

A substance that can either donate or accept a proton (H+).

Arrhenius acid-base definition

A model of acid-base behaviour in which an acid is a substance that yields H3O+ when dissolved in water, and a base is a substance that yields OH− when dissolved in water.

Autoionization (self-ionization)

A reaction in which two molecules of a substance react to give ions. The most important example is for water

base-dissociation (base-ionization) constant (Kb)

An equilibrium constant for the reaction of a base (B) with H2O to yield the conjugate acid (BH+ and OH−)

**Brønsted-Lowry acid-base definition**

A model of acid-base behavior based on proton transfer, in which an acid and a base are defined, respectively, as a species that donates a proton and one that accepts a proton.

Conjugate acid-base pair

Two species related to each other through the gain or loss of a proton; the acid has one more proton than its conjugate base.

**hydronium ion (H3O+)**

A proton covalently bonded to a water molecule.

ion-product constant for water (Kw)

The equilibrium constant for the autoionization of water; equal to 1.0 × 10−14 at 298 K (Kw = \[H3O+\]\[OH-\]

Leveling effect

The inability of a solvent to distinguish the strength of an acid (or base) that is stronger than the conjugate acid (or conjugate base) of the solvent.

Lewis acid-base definition

A model of acid-base behaviour in which acids and bases are defined, respectively, as species that accept and donate an electron pair.

Neutralization

The process that occurs when an H+ ion from an acid combines with an OH− ion from a base to form H2O.

pH

The negative of the common logarithm of \[H3O+\]

polyprotic acid

An acid with more than one ionizable proton.

Bronsted-Lowry base

A species that accepts an H+ ion (a proton acceptor)

Bronsted-Lowry acid

A species that donates an H+ ion (a proton donor)