Question

Consider the following statements. Write out an example reaction and \(K\) expression that is associated with each statement. a. The autoionization of water. b. An acid reacts with water to produce the conjugate base of the acid and the hydronium ion. c. A base reacts with water to produce the conjugate acid of the base and the hydroxide ion.

Short answer

a. Example reaction: \( 2H_2O \longleftrightarrow H_3O^+ + OH^-\) Equilibrium constant expression: \[K_w = [H_3O^+][OH^-]\] b. Example reaction: \( CH_3COOH + H_2O \longleftrightarrow CH_3COO^- + H_3O^+\) Equilibrium constant expression: \[K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}\] c. Example reaction: \( NH_3 + H_2O \longleftrightarrow NH_4^+ + OH^-\) Equilibrium constant expression: \[K_b = \frac{[NH_4^+][OH^-]}{[NH_3]}\]

Step-by-step solution

Example reaction

The autoionization of water can be written as: \( 2H_2O \longleftrightarrow H_3O^+ + OH^-\)

Equilibrium constant expression

The equilibrium constant expression, K, for this reaction is called the ion product of water (Kw) and is expressed as: \[K_w = [H_3O^+][OH^-]\] #b. An acid reacts with water to produce the conjugate base of the acid and the hydronium ion#

Example reaction

We'll use acetic acid (CH3COOH) as our example. The reaction between acetic acid and water can be written as: \( CH_3COOH + H_2O \longleftrightarrow CH_3COO^- + H_3O^+\)

Equilibrium constant expression

The equilibrium constant expression, K, for this reaction is called the acid dissociation constant (Ka) and is expressed as: \[K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}\] #c. A base reacts with water to produce the conjugate acid of the base and the hydroxide ion#

Example reaction

We'll use ammonia (NH3) as our example base. The reaction between ammonia and water can be written as: \( NH_3 + H_2O \longleftrightarrow NH_4^+ + OH^-\)

Equilibrium constant expression

The equilibrium constant expression, K, for this reaction is called the base dissociation constant (Kb) and is expressed as: \[K_b = \frac{[NH_4^+][OH^-]}{[NH_3]}\]