[H+]=0.0039 M ; [CHO−2]=0.0039 M ; and [HCHO2]=0.0845 M. HCHO2(aq)↽−−⇀H+(aq)+CHO−2(aq)

Question

At equilibrium, an aqueous solution of formic acid (HCHO2) has these concentrations: [H+]=0.0039 M; [CHO−2]=0.0039 M; and [HCHO2]=0.0845 M.

HCHO2(aq)↽−−⇀H+(aq)+CHO−2(aq)

What is the value of K of this equilibrium?

𝐾=

Does the equilibrium lie to the right or to the left?

right

left

Answer 1

You MUST be careful how you write chemical formulas. CHO-2 is not the same as CHO2-. In the current problem we are dealing with HCHO2, and CHO2- or better written as CHO₂^-

K = [H⁺][CHO₂^-] / [HCHO₂] = (0.0039)(0.0039) / 0.0845

K = 1.8x10^-4

The equilibrium lies to the LEFT since the value of K is < 1.