What is the value of K in this equilibrium?

Question

At equilibrium, an aqueous solution of formic acid (HCHO₂) has these concentrations: [H⁺] =0.0067 M;

[CHO₂^-]= 0.0067 M; and [HCHO₂]=0.249

HCHO₂(aq) ⇌ H⁺ (aq) +CHO₂^- (aq)

What is the value of K in this equilibrium?

K=?

Answer 1

HCHO₂ <==> H⁺ + CHO₂

K = [H⁺][CHO₂] / [HCHO₂]

Plug in values that are given:

K = [0.0067][0.0067] / [0.249]

K = 1.80x10^-4