Question

Ammonia produced by 0.75 g substance during nitrogen estimation in an organic compound by Kjeldahl’s method requires 15 cm3 of 0.5 N H2SO4. The percentage of nitrogen in the compound is??​

Answer 1

Given:

m = 0.5 gm

N = 0.5 N

Volume of H2SO4 consumed, (V-V₁/2) = 15 cm³ = 15 ml

To Find:

The percentage of nitrogen in the compound.

Calculation:

- We know that for H2SO4, n = 2

⇒ M = N / n

⇒ M = 0.5 / 2

⇒ M = 0.25 M

- For Kjelhdal's method:

% of N = 1.4 × M × 2 × (V-V₁/2) / m

⇒ % of N = 1.4 × 0.25 × 2 × 15 / 0.75

⇒ % of N = 14 %

- So the percentage of nitrogen in the compound is 14 %