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`1 M `benzoic acid `(pK_(a)=4.2)` and `1 M C_(6)H_(5)COONa` solutions are given separately. What is the volume of benzoic acid required to prepare a `93mL` buffer solution of `pH=4.5`? |
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Answer» `pH = pK_(a) + (log)([HCO_(3)^(-)])/([C_(6)H_(5)CO_(3)]) rArr 4.5 = 4.2 + log ((V_(2))/(V_(1))) rArr (V_(2))/(V_(1)) = 2` `:.` volume of `C_(6)H_(5)COONa` required `= V_(@) = 62 mL` volume of `C_(6)H_(5)COOH` required `= V_(1) = 31 mL`. |
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