Book: Key Terms: 18

Organic molecules whose colors depend on the acidity of the solution in which they are dissolved.

The equilibrium constant specifically for acid dissociation: K_a = [H3O+][A-] / [HA], for weak acid HA.

The product of a Lewis acid-base reaction: a single species that contains a new covalent bond. A + B ⇌ A—B (adduct).

A definition of acids and bases that classifies these substances according to their formulas and behaviors in water: an acid is a substance with H in its formula that dissociates in water to yield a H3O+, while a base is a substance with OH in its formula that dissociates in water to yield OH-.

The equilibrium process by which water dissociates very slightly into H3O+ and OH-.

The equilibrium expression for the dissociation of base in water: K_a = [BH+][OH-] / [B] for base B.

A definition for acids and bases that describes acids as proton (p+ or H+) donors while bases are considered proton acceptors.

Any acid has a conjugate base, and vice versa for bases. For any conjugate acid-base pair, the conjugate base has one fewer H and one more negative charge than the acid, while the conjugate acid has one more H and one fewer negative charge than the base.

The charge density of the proton is so strong that it attracts water molecules especially strong,y covalently bonding to one of the lone electron pairs of the water molecule’s O atom. The result is hydronium, or H3O+. [H3O+] is equivalent to [H+].

To describe the autoionization of water, K_w is constructed to reflect the dissociation of water molecules into H3O+ and OH-: K_w = [H3O+][OH-], but since the concentration of pure water is essentially constant, K_w is also essentially constant at K_w = 1.0×10^-14, and K_w at 25 C always takes this value.

Water exerts this effect on any strong acid or base by reacting with it to form the products of the autoionization of water. Acting as a base, water levels the strength of all strong acids by making them appear equally strong, and acting as an acid, it levels the strength of all strong bases.

A definition of acids and bases which holds that bases are any species that donate electron pairs to form bonds, while acids are any species that accept electron pairs to form bonds.

In the Arrhenius sense, neutralization occurs when H+ from an acid and the OH- from a base react to form H2O.

pH = - log [H3O+]

Acids with more than one ionizable proton.

Bases according to the Bronsted-Lowry definition; any species that accepts an H+ ion.

Acids according to the Bronsted-Lowry definition; any species that donates an H+ ion.