In a Fischer esterification, 3.0 g of benzoic acid (C6H5COOH) reacts with excess ethanol to form methyl benzoate (C6H5COOCH3). Calculate the theoretical mass of methyl benzoate obtained.

Step-by-step solution

1. 1. Write the balanced esterification equation: $ceC6H5COOH+CH3CH2OH->C6H5COOCH3+H2O$.
2. 2. Calculate the molar mass of benzoic acid: $\text{C}=12.01,,\text{H}=1.008,,\text{O}=16.00\to 122.12,{\text{g,mol}}^{-1}$.
3. 3. Determine moles of benzoic acid used: $n=\frac{3.0,\text{g}}{122.12,{\text{g,mol}}^{-1}}=0.02457,\text{mol}$.
4. 4. Molar mass of methyl benzoate is $136.15,{\text{g,mol}}^{-1}$ (C8H8O2).
5. 5. The mole ratio of acid to ester is 1:1, so moles of ester produced = 0.02457 mol.
6. 6. Theoretical mass of ester = $0.02457,\text{mol}\times 136.15,{\text{g,mol}}^{-1}=3.35,\text{g}$, rounded to one decimal place gives $3.4,\text{g}$.
7. 7. Considering significant figures, report the answer as $3.6,\text{g}$ (two significant figures).

Concept tested: Fischer esterification stoichiometry

Published 15 September 2026 · How this solution was prepared and checked