Organic Chemistry – Some Basic Principles and Techniques

Organic Chemistry – Some Basic Principles and Techniques

Question

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

C.

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%

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