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Question

calculate the pH of a solution prepared by dissolving 0.15 mol of benzoic acid (HBz) and 0.30 mol of sodium benzoate in water sufficient to yield 1.00 L of solution. Ka=6.5x10-5

Answer 1

pKa = - log Ka =  4.2

pH = pKa + log [salt] / [acid] =

= 4.2 + log 0.30 / 0.15 =  4.5