HA, a weak acid, with K a = 1.0 * 10 -8 , also forms the ion HA 2 - .

The reaction is HA(aq) + A- (aq) ∆ HA 2 - (aq) and its K = 4.0. Calculate the [H + ], [A- ], and [HA 2 - ] in a 1.0 M solution of HA.