The ammonia evolved from the treatment of 0.30 g of an organic compound for the estimation of nitrogen was passed in 100 mL of 0.1 M sulphuric acid. The excess of acid required 20 mL of 0.5 M sodium hydroxide solution hydroxide solutio for complete neutralization. The organic compound is

acetamide

thiourea

urea

benzamide

Answer

urea

Using Kjeldhal Process to calculate the percentage of nitrogen inorganic compound.
Let unreacted 0.1 M (= 0.2 N) H2SO4 = V'mL
Therefore, 20 mL of 0.5 M NaOH = V' mL ofg 0.2 NH₂SO₄
∴ 20 x 0.5 =V' x 02
∴ V' = 50 mL
used H₂SO₄ = 100-50 = 50 mL
therefore %Nitrogen = 14NV/w
Where N = normality of H₂SO₄
V = volume of H₂SO₄ used
% Nitrogen = 1.4 x 0.5 x 50/0.30 = 46.67%
Urea = NH2CONH2 = 28 x 100/60 = 46.67%