etermine the pH of the following solutions, given that Ka (HF) = 6.8 x 10-4. Hint: 1. Diagnose the scenario (i.e. strong acid + weak base, etc.), 2. If buffer solution, make use of Henderson-Hasselback eqn and 3. If strong acid/base added to buffer, write out reaction with strong acid or base on the left hand side, then calculate ICE change. a. 0.5 moles of NaF (2 marks) b. A solution with 0.5 moles HF (Ka = 6.8 x 10-4) and 0.5 moles NaF, to which 0.1 moles HCl is added. (2 marks)