Question

A student has planned to prepare acetanilide from aniline using acetic anhydride. The student has started from 9.3 g of aniline. However, the student has managed to obtain 11 g of dry acetanilide. The % yield of this reaction is

• A. 97.5%
• B. 81.5%
• C. 59.5%
• D. 72.5%

Hint:

Always calculate percentage yield using actual yield over theoretical yield.

Answer 1

The Correct Option is B

Step 1: Calculating moles of aniline.
Molar mass of aniline = 93 g mol⁻¹
\[ \text{Moles of aniline} = \frac{9.3}{93} = 0.1 \text{ mol} \]
Step 2: Stoichiometry of the reaction.
1 mole of aniline produces 1 mole of acetanilide.
Molar mass of acetanilide = 135 g mol⁻¹.
Step 3: Theoretical yield of acetanilide.
\[ \text{Theoretical yield} = 0.1 \times 135 = 13.5 \text{ g} \]
Step 4: Percentage yield calculation.
\[ \text{Percentage yield} = \frac{11}{13.5} \times 100 = 81.5 \]