Acetic acid is a weak acid that dissociates into the acetate ion and a proton in aqueous solution: HC₂H₃O₂ (aq) C₂H₃O₂^- (aq) + H⁺ (aq)
At equilibrium at 25 °C a 0.100 M solution of acetic acid has the following concentrations:
[HC₂H₃O₂] = 0.0990 M, [C₂H₃O₂^-] = 1.33 × 10^-3M and [H+] = 1.33 × 10^-3M. The equilibrium constant, K_eq, for the ionization of acetic acid at 25 °C is ________.

Question

Acetic acid is a weak acid that dissociates into the acetate ion and a proton in aqueous solution: HC₂H₃O₂ (aq)

Acetic acid is a weak acid that dissociates into the acetate ion and a proton in aqueous solution: HC<sub>2</sub>H<sub>3</sub>O<sub>2</sub> (aq) C<sub>2</sub>H<sub>3</sub>O<sub>2</sub><sup>-</sup> (aq) + H<sup>+</sup> (aq) At equilibrium at 25 °C a 0.100 M solution of acetic acid has the following concentrations: [HC<sub>2</sub>H<sub>3</sub>O<sub>2</sub>] = 0.0990 M, [C<sub>2</sub>H<sub>3</sub>O<sub>2</sub><sup>-</sup>] = 1.33 × 10<sup>-3</sup><sup> </sup>M and [H+] = 1.33 × 10<sup>-3</sup><sup> </sup>M. The equilibrium constant, K<sub>eq</sub>, for the ionization of acetic acid at 25 °C is ________. A) 5.71 × 10<sup>4</sup> B) 0.100 C) 1.75 × 10<sup>-7</sup> D) 1.79 × 10<sup>-5</sup> E) 5.71 × 10<sup>6</sup>

C₂H₃O₂^- (aq) + H⁺ (aq)
At equilibrium at 25 °C a 0.100 M solution of acetic acid has the following concentrations:
[HC₂H₃O₂] = 0.0990 M, [C₂H₃O₂^-] = 1.33 × 10^-3M and [H+] = 1.33 × 10^-3M. The equilibrium constant, K_eq, for the ionization of acetic acid at 25 °C is ________.

Quizplus · Accepted Answer

The equilibrium expression for the ionization of acetic acid is:

KS1U1B1eqS1U1B0 = [CS1U1B12S1U1B0HS1U1B13S1U1B0OS1U1B12S1U1B0S1U1P1-S1S1P0][HS1U1P1+S1S1P0]/[HCS1U1B12S1U1B0HS1U1B13S1U1B0OS1U1B12S1U1B0]

Substituting the given concentrations at equilibrium:

KS1U1B1eqS1U1B0 = (1.33 × 10S1U1P1-3S1S1P0S1U1P1 S1S1P0)² / (0.0990 S1U1P0) = 1.79 × 10S1U1P1-5S1S1P0

Therefore, the correct answer is D.

Acetic Acid Is a Weak Acid That Dissociates into the Acetate