Given the two reactions H2S(aq)⇌HS−(aq)+H+(aq), K1 = 9.11×10−8, and
HS−(aq)⇌S2−(aq)+H+(aq), K2 = 1.41×10−19,
what is the equilibrium constant Kfinal for the following reaction?
S2−(aq)+2H+(aq)⇌H2S(aq)