If 2.5 g of formic acid (M = 46.03 g mol⁻¹) reacts with excess methanol in the presence of concentrated H₂SO₄ to give methyl formate (M = 70.07 g mol⁻¹), calculate the theoretical mass of methyl formate obtained.

medium 2 marks Class 12 · Chemistry · Aldehydes Ketones and Carboxylic Acids

Answer

3.80 g

The correct answer is 3.80 g — Step 5: Thus the theoretical yield of methyl formate is 3.80 g.

Step-by-step solution

Step 1: Calculate moles of formic acid: 2.5 g ÷ 46.03 g mol⁻¹ = 0.0543 mol.
Step 2: In Fischer esterification, the stoichiometry is 1:1 between acid and alcohol → 0.0543 mol of methyl formate is produced.
Step 3: Convert moles of product to mass: 0.0543 mol × 70.07 g mol⁻¹ = 3.804 g.
Step 4: Round to two significant figures as required: 3.80 g.
Step 5: Thus the theoretical yield of methyl formate is 3.80 g.

Common mistake: Using the molar mass of the acid instead of the ester in the final calculation

Concept tested: Fischer esterification stoichiometry