The equilibrium constant kc for the reaction hf(aq) + h2o(l) h3o+(aq) +f-(aq) is 3.5 x 10-4. what is the equilibrium concentration of h3o+ if the initial concentration of hf is 1.0 m?
according to the reaction equation: Hf(aq) + H2O (l)↔ H3O+ (aq) + F(aq)
initial 1 m 0 0 -X +X +X (1-x) X X We assumed that [H3O+] = X so. at eqilibrium: Kc = [H3O] [ F] / [Hf] when we have Kc so by substitution: 3.5x10^-4 = X^2 / (1-X) ∴X^2 = 3.5x10^-4 - 3.5x10^-4 X X^2 + 3.5x10^-4 X - 3.5x10^-4= Zero by solving this equation: (X-1.9x10^-2)(X + 1.9x10^-2) = Zero ∴X = 1.9x10^-2 ∴ the equilibrium constatnt of H3O = 1.9x10^-2 M
