Question

In Kjeldahl's method, nitrogen present is quantitatively converted to __________.

• A. $N_2$
• B. $(N{H}_4{)}_{2}S{O}_4$
• C. $N{O}_2$
• D. $N{H}_3$

Answer 1

Answer: (B)

$(N{H}_4{)}_{2}S{O}_4$

This method is based on the fact that when the nitrogenous compound is heated with concentrated sulphuric acid in presence of copper sulphate, the nitrogen present in the compound is quantitatively converted to ammonium sulphate. The ammonium sulphate so formed is decomposed with excess of alkali and the ammonia evolved is estimated volumetrically. The percentage of nitrogen is then calculated from the amount of ammonia.