Question

5.8 g of Aniline is converted into benzanilide with some reaction sequences. Calculate the mass of benzanilide formed, if percentage yield of reaction is 82%. \[ \text{Ph} - \text{COCl} + \text{PhNH}_2 \xrightarrow{\text{Py}} \text{Benzanilide} \]

Hint:

To calculate the actual yield of a reaction, multiply the theoretical yield by the percentage yield.

Answer 1

Correct Answer: 3

Aniline (\(\text{PhNH}_2\)) reacts with benzoyl chloride (\(\text{PhCOCl}\)) in the presence of pyridine (Py) to form benzanilide. To calculate the mass of benzanilide formed, we first need to determine the theoretical yield based on the initial mass of aniline, then account for the 82% reaction yield.
1. **Molar Mass Calculation:**
 a. Molar mass of aniline (\(\text{C}_6\text{H}_5\text{NH}_2\)): \(93.13\,\text{g/mol}\).
 b. Molar mass of benzanilide (\(\text{C}_{13}\text{H}_{11}\text{NO}\)): \(197.24\,\text{g/mol}\).
2. **Moles of Aniline:**
 a. Moles = \(\frac{\text{mass}}{\text{molar mass}}\)
 b. Moles of aniline = \(\frac{5.8\,\text{g}}{93.13\,\text{g/mol}} \approx 0.0623\,\text{mol}\).
3. **Theoretical Yield of Benzanilide:**
 a. 1:1 molar ratio between aniline and benzanilide. Thus, moles of benzanilide = 0.0623 mol.
 b. Theoretical mass of benzanilide = \(0.0623\,\text{mol} \times 197.24\,\text{g/mol} \approx 12.29\,\text{g}\).
4. **Actual Yield Calculation:**
 a. Actual mass = \(\text{Theoretical mass} \times \frac{\text{Percentage yield}}{100}\)
 b. Actual mass of benzanilide = \(12.29\,\text{g} \times \frac{82}{100} \approx 10.08\,\text{g}\).
5. **Verification Against Range:**
 a. Calculated mass (10.08 g) is not within the range of 3 to 3. This suggests an ambiguity in the range context, potentially unrelated to the solution value directly.
**Conclusion:** The mass of benzanilide formed, given an 82% yield, is approximately 10.08 g.