A) Lactic acid, C3H6O3 is a weak organic acid. A buffer is prepared by dissolving 0.5 mol of lactic acid, HLac (Ka = 1.4 x 10-4 ) and 0.5 mol of sodium lactate, NaLac in enough water to make 500 mL of solution. Calculate [H3O+ ] and PH of the buffer. B) Calculate the PH of the above buffer after the addition of a) 0.12 mole of HCl b) 0.12 mole of NaOH