Chemistry - GOC Question with Solution | TestHub

An acid-base equilibrium goes forward when the stronger acid and the stronger base give the weaker acid and the weaker base.

(A) Phenol ($\mathrm{p}{K}_{\mathrm{a}}$ 10) is a weaker acid than ${\mathrm{H}}_2\mathrm{C}{\mathrm{O}}_3$ (6.4), so the reaction goes backward. No.

(B) Acetic acid (4.8) is a stronger acid than phenol (10): the reaction goes forward. Yes.

(C) Ethyne ($\mathrm{p}{K}_{\mathrm{a}}$ 25) is a much stronger acid than ammonia (35): forward. Yes.

(D) Ethanol (about 16) is slightly weaker than water (15.7), so the equilibrium lies on the left. No.

Answer: (B), (C).