A buffer contains 0.010 mol of lactic acid (pKa = 3.86) and 0.050 mol of sodium lactate per liter. (a) Calculate the pH of the buffer. (b) Calculate the change in pH when 5 mL of 0.5 M HCl is added to 1 L of the buffer. (c) Calculate the change in pH when 5 mL of 0.5 M NaOH is added to 1 L of the buffer. (d) What pH change would you expect if you separately added the same quantity of HCl and NaOH to 1 L of pure water?

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