Question

In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralized 10 mL of 1 M H₂SO₄. The percentage of nitrogen in the soil is

(a) 37.33

(b) 45.33

(c) 35.33

(d) 43.33

Answer 1

The correct option is: (a) 37.33

Explanation:

H₂SO₄ + 2NH₃ → (NH₄)₂SO₄ 

10 mL of 1 M H₂SO₄ = 10 mmol

             [.^. . M x V_(mL) = mmol]

NH₃ consumed = 20 mmol

Acid used for the absorption of ammonia 

= 20 - 10 mmol

= 10 mL of 2 N (or 1 M) H₂SO₄