1. How many moles of HF (pKa = 3.14) must be added to 500mL of 0.30M sodium fluoride (NaF) to give a buffer of pH 3.5? Ignore volume changes due to addition of hydrofluoric acid.
2. What is the molarity of CH3COO- in a buffer with a final pH of 5.20 if the concentration of CH3COOH is 0.25M? (pKa of CH3COOH is 4.7)