In a Kjeldahl determination, the ammonia from 0.500 g of an organic compound is absorbed in 50.0 mL of 0.100 M H2SO4. The unreacted acid needs 21.0 mL of 0.200 M NaOH. Find the mass percentage of nitrogen in the compound (N = 14; one decimal place).

JEE Advanced levelNumerical answerDifficulty 3 of 3eq154

In a Kjeldahl determination, the ammonia from 0.500 g of an organic compound is absorbed in 50.0 mL of 0.100 M $H X_{2} SO X_{4}$ . The unreacted acid needs 21.0 mL of 0.200 M NaOH. Find the mass percentage of nitrogen in the compound (N = 14; one decimal place).

Numerical answer type, answer in %, tolerance 0.06.

Acid taken = 0.100

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50.0 = 10.0 meq. Excess acid = 0.200

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21.0 = 4.20 meq, so ammonia absorbed = 5.80 meq = 5.80 mmol N (n = 1). Mass of N = 5.80

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14 = 81.2 mg. Percentage = 0.0812/0.500

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100 = 16.2 %.