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Some Basic Concepts of Chemistry
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12/08/2021 10:56 am
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A gaseous compound of nitrogen and hydrogen contains 12.5% (by mass) of hydrogen. The density of the compound relative to hydrogen is 16. The molecular formula of the compound is:
(a) NH2
(b) N3H
(c) NH3
(d) N2H4
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12/08/2021 11:04 am
Correct answer: (d) N2H4
Explanation:
In an unknown compounds containing N and H given % of H = 12.5%
∴ % of N = 100 – 12.5 = 87.5%
Element: H
Percentage: 12.5%
Atomic ratio: \(\frac{12.5}{1}\) = 12.5
Simple ratio: \(\frac{12.5}{6.25}\) = 2
Element: N
Percentage: 87.5%
Atomic ratio: \(\frac{87.5}{14}\) = 6.25
Simple ratio: \(\frac{6.25}{6.25}\) = 1
2 × vapour density = Mol. wt = mol wt.
= 16 × 2 = 32.
Molecular formula = n × empirical formula
mass n = \(\frac{32}{16}\) = 2
∴ Molecular formula of the compound will be = (N2H2)2
= N2H4