Question

You have 1L of a solution which contains: 0.100M aqueous ammonia and 0.200M ammonium chloride. What is the pH if 0.02 moles of NaOH pellets are added? Kb for NH3 = 1.8 x 10-5 (I keep getting 9.69 an

d the answer should fall between 9.08 and 9.13 apparently)