Question

Given the reaction sequence:

The percentage of Nitrogen in compound E is:

Hint:

To calculate the percentage of an element in a compound, divide the atomic mass of the element by the molecular mass of the compound and multiply by 100.

Answer 1

Correct Answer: 20

To find the percentage of nitrogen in compound E, we first need to understand the reaction sequence:

1. The benzene ring undergoes nitration with concentrated HNO₃ and H₂SO₄ to form nitrobenzene (compound A).
2. Nitrobenzene is reduced using Sn/HCl to form aniline (compound B).
3. Aniline is acetylated with acetic anhydride to form acetanilide (compound C).
4. Nitration of acetanilide with concentrated HNO₃ and H₂SO₄ forms a nitro derivative (compound D).
5. Acid hydrolysis of this derivative gives compound E, which is para-nitroaniline.

Now, let's calculate the percentage of nitrogen in para-nitroaniline (C₆H₆N₂O₂):

• Molar mass of C₆H₆N₂O₂ = (6 × 12.01) + (6 × 1.01) + (2 × 14.01) + (2 × 16.00) = 138.12 g/mol
• Mass of nitrogen = 2 × 14.01 = 28.02 g
• Percentage of nitrogen = (28.02 / 138.12) × 100 = 20.29%

The computed percentage of nitrogen in compound E matches the expected range of 20.20%, confirming our solution is correct.