A buffer solution contains 0.23 mol of carbonic acid (H2CO3) and 0.55 mol of sodium hydrogen carbonate (NaHCO3) in 2.10 L. The Ka of carbonic acid (H2CO3) is Ka = 4.3e-07. (a) What is the pH of this buffer? pH = (b) What is the pH of the buffer after the addition of 0.13 mol of NaOH? (assume no volume change) pH = (c) What is the pH of the original buffer after the addition of 0.34 mol of HI? (assume no volume change) pH =