Neco Model Questions Vol1 2023 Chemistry Question 25

In a Fischer esterification, 0.050 mol of benzoic acid (\(C_6H_5COOH\), \(M = 122.12\ \text{g mol}^{-1}\)) is mixed with 0.040 mol of ethanol (\(C_2H_5OH\), \(M = 46.07\ \text{g mol}^{-1}\)) in the presence of excess \(H_2SO_4\). The equilibrium constant at reflux is \(K = 4.0\). After equilibrium is reached, the ester is isolated and 4.00 g of ethyl benzoate is obtained. (a) Identify the limiting reagent. (b) Calculate the theoretical maximum mass of ethyl benzoate. (c) Using the equilibrium constant, determine the mass of ester that would be present at equilibrium. (d) Compute the percent recovery based on the isolated mass. (e) If the isolated ester is dissolved in 250 mL of water and assumed to hydrolyse completely back to benzoic acid (\(K_a = 6.3\times10^{-5}\)), estimate the pH of the solution.