50.oomL of carbonic acid solution with [H_2CO_3] = 0.00735 M is titrated with 0.100 M KOH. Determine the pH of the solution when 70.00mL of OH have been added.
H_2CO_3aq + H_2O <--> HCO_3 + H3O Ka1= 4.46x10^-7
HCO_3 + H_2O <--> CO_3 ^-2 + H_3O Ka2= 4.69x10-11