In the following reaction: HC₂H₃O₂ ⇌ H⁺ + C₂H₃O₂^-, if [HC₂H₃O₂] = 0.28 M and the pH = 5.0, what is K?

Question

Quizplus · Accepted Answer

The reaction involves the dissociation of a weak acid into its conjugate base and a hydrogen ion. Given the pH is 5.0, the concentration of hydrogen ions [H+] can be calculated using the pH formula: pH = -log[H+], which gives [H+] = 10^-5 M. Assuming the dissociation is small compared to the initial concentration of the acid, the concentration of the conjugate base will also be approximately 10^-5 M. The equilibrium expression for the dissociation of a weak acid (HA ⇌ H+ + A-) is K = [H+][A-]/[HA]. Substituting the given and calculated values: K = (10^-5)(10^-5)/0.28 = 3.57 × 10^-10, which matches choice A.

In the Following Reaction: HC2H3O2 ⇌ H+ + C2H3O2-, If

In the Following Reaction: HC₂H₃O₂ ⇌ H⁺ + C₂H₃O₂^-, If