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For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in 60 mL of M/10 sulphuric acid. The unreacted acid required 20 Ml of M/10 sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound isA. 0.05B. 0.06C. 0.1D. 0.03 |
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Answer» Correct Answer - C Volume of the acid taken = 60 mL of M/10 `H_(2)SO_(4)` Let the acid left unused = v mL of M/10 `H_(2)SO_(4)` Volume of M/10 NaOH used to neutralize the unreacted acid = 20mL Applying molarity equation, `underset("(Acid)")(n_(a)M_(a)V_(a)) = underset("(Base)")(n_(b)M_(b)V_(b))` where `n_(a), M_(a)` and `V_(a)` are the basicity, molarity and volume of the acid and `n_(b), M_(b)` and `V_(b)` are the acidity, molarity and volume of the base or `2 xx (1)/(10) xx v = 1 xx (1)/(10) xx 20` `:. v = 10 mL` `:.` Volume of the acid used = 60 - 10 = 50 mL of M/10 `H_(2)SO_(4)` Now % of N `= (1.4 xx "Molarity" xx "Volume" xx "Basicity of the acid used")/("Weight of the substance taken")` `= (1.4 xx 1 xx 50 xx 2)/(10 xx 1.4) = 10.0` |
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