A buffer solution contains 0.71 mol of boric acid (H3BO3) and 0.53 mol of sodium dihydrogen borate (NaH2BO3) in 4.00 L. The Ka of boric acid (H3BO3) is Ka = 5.8e-10. What is the pH of the buffer after the addition of 0.50 mol of NaOH? (assume no volume change) I already know the pH for the first part. it's 9.11 i just can't figure out the pH after the addition of 0.50 mol of NaOH