Chemistry
A gaseous hydrocarbon contains 82.76% of carbon. Given that it's vapours density is 29, find it's molecular formula.
[C = 12, H = 1]
Stoichiometry
ICSE 2016
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Answer
Element | % composition | At. wt. | Relative no. of atoms | Simplest ratio |
---|---|---|---|---|
Carbon | 82.76 | 12 | = 6.89 | = 1 |
Hydrogen | 17.24 | 1 | = 17.24 | = 2.5 |
Simplest ratio of whole numbers = C : H = 1 : 2.5 = 2 : 5
Hence, empirical formula is C2H5
Empirical formula weight = 2(12) + 5(1) = 29
V.D. = 29
Molecular weight = 2 x V.D. = 2 x 29
∴ Molecular formula = n[E.F.] = 2[C2H5] = C4H10
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