JEE Main 202622 JanuaryEvening Shift
- Exam
- JEE Main
- Year
- 2026
- Date
- 22 January
- Shift
- Evening Shift
- Subject
- Chemistry
- Chapter
- General Organic Chemistry
JEE Main 2026 · 22 January · Evening Shift · Chemistry · General Organic Chemistry
When 1 g of compound (X) is subjected to Kjeldahl's method for...
When 1 g of compound is subjected to Kjeldahl's method for estimation of nitrogen, 15 mL 1 M was neutralized by ammonia evolved. The percentage of nitrogen in compound is :
Options
- A0.21
- B21
- C42
- D0.42
Correct answer
C. 42
Step-by-step solution
In Kjeldahl's method, nitrogen in the compound is converted to NH₃.
The ammonia is absorbed and reacts with H₂SO₄ according to: .
Given that 15 mL of 1 M H₂SO₄ was neutralized:
Moles of H₂SO₄ = 15 × 10⁻³ mol.
From stoichiometry, 1 mol H₂SO₄ reacts with 2 mol NH₃.
Therefore, moles of NH₃ = 2 × 15 × 10⁻³ = 0.030 mol.
Since each NH₃ contains 1 nitrogen atom:
Moles of N = 0.030 mol.
Mass of N = 0.030 × 14 = 0.42 g.
Percentage of N in compound = (0.42/1) × 100 = 42%.
The ammonia is absorbed and reacts with H₂SO₄ according to: .
Given that 15 mL of 1 M H₂SO₄ was neutralized:
Moles of H₂SO₄ = 15 × 10⁻³ mol.
From stoichiometry, 1 mol H₂SO₄ reacts with 2 mol NH₃.
Therefore, moles of NH₃ = 2 × 15 × 10⁻³ = 0.030 mol.
Since each NH₃ contains 1 nitrogen atom:
Moles of N = 0.030 mol.
Mass of N = 0.030 × 14 = 0.42 g.
Percentage of N in compound = (0.42/1) × 100 = 42%.