JEE MAIN - Chemistry (2022 - 24th June Evening Shift - No. 19)
0.2 g of an organic compound was subjected to estimation of nitrogen by Dumas method in which volume of N2 evolved (at STP) was found to be 22.400 mL. The percentage of nitrogen in the compound is _________. [nearest integer]
(Given : Molar mass of N2 is 28 g mol$$-$$1. Molar volume of N2 at STP : 22.4 L)
Answer
14
Explanation
Given volume of N2 = 22.400 mL
$$\therefore$$ Moles of N2 = $${{22.400} \over {22400}} = {10^{ - 3}}$$ mole
$$\therefore$$ Moles of N atoms = 2 $$\times$$ 10$$-$$3 mole
$$\therefore$$ Weigh of N atoms = 14 $$\times$$ 2 $$\times$$ 10$$-$$3 mole
= 28 $$\times$$ 10$$-$$3 mole
$$\therefore$$ % of N atom in the compound
$$ = {{28 \times {{10}^{ - 3}}} \over {0.2}} \times 100$$
= 14
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