A buffer is made by adding 0.300 mol CH3COOH and 0.300 mol CH3COONa to enough water to make 1L L of solution. The pH of the buffer is 4.74. Calculate the pH of this solution after 7.8 0mL of 4.0 M NaOH(aq) solution is added. Ka of acetic acid = 1.8x10-5