A buffer has 0.050 mol of sodium lactate and 0.010 mol of lactic acid (pKa = 3.86) per liter.
1. Determine the pH of the buffer.
2. Determine the pH when 5 mL of 0.5 M HCl is added to 1 L of the buffer.
3. Explain what pH would you expect if you added the same quantity of HCl to 1 L of pure water?