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

Answer 1

HCHO₂ <==> H⁺(aq) + CHO₂^-(aq)

K = [H⁺][CHO₂^-] / [HCHO₂]

K = (0.0039)(0.0039) / (0.0845)

K = 1.8x10^-4