Malonic acid, HO2CCH2CO2H, is a diprotic acid. The pKa for the loss of the first proton is

Question:

Malonic acid, HO2CCH2CO2H, is a diprotic acid. The pKa for the loss of the first proton is 2.83; the pKa for the loss of the second proton is 5.69.
(a) Explain why malonic acid is a stronger acid than acetic acid (pKa = 4.75).
(b) Explain why the anion, -O2CCH2CO2H, is so much less acidic than malonic acid itself.