Neco Model Questions Vol1 2022 Chemistry Question 37
Practice objective / multiple choice question 37 from the 2022 Neco Model Questions Vol1 Chemistry examination.
Acetic acid (\(\mathrm{CH_3COOH}\)) has \(K_a = 1.8\times10^{-5}\) and molar mass \(60\ \text{g mol}^{-1}\). Propionic acid (\(\mathrm{C_2H_5COOH}\)) has \(K_a = 1.3\times10^{-5}\) and molar mass \(74\ \text{g mol}^{-1}\). A 250 mL aqueous solution is to be prepared that has a pH of 4.75 and a total acid concentration (\([\text{HA}]_{\text{total}}\)) of \(2.0\times10^{-5}\ \text{mol L}^{-1}\). Assuming the two acids dissociate independently and that each obeys the approximation \([\mathrm{H^+}] \approx \sqrt{K_a C}\), determine the masses of acetic acid and propionic acid that must be dissolved to obtain the required solution.
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This is Neco Model Questions Vol1 2022 Chemistry Question 37. It is one of the objective questions from the 2022 Neco Model Questions Vol1 Chemistry examination.
Difficulty level: Hard .
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