Consider the following general reaction (acetic acid + water in equilibrium with hydronium + acetate):
HC2H3O2 (aq) + H2O (l) ? H3O+ (aq) + C2H3O2- (aq) Kc = 1.8 x 10-5 (at 25 ºC)
If a solution initially contains (5.6x10^-1) M of HC2H3O2, (and no H3O+ or C2H3O2- ), what is the equilibrium concentration of H3O+ (aq) in the mixture?