Chemistry

Problem

A buffer solution is made by dissolving 0.50 g of benzoic acid (molar mass 122.12 g·mol

^{-1}

) and 0.58 g of sodium benzoate (molar mass 144.11 g·mol

^{-1}

) in enough water to form 250 mL of solution at 25 °C. The

pK_a

of benzoic acid is 4.20. Determine the pH of this buffer.