Chemistry
Find the molecular formula of a hydrocarbon having vapour density 15, which contains 20% of Hydrogen.
Mole Concept
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Answer
| Element | % composition | At. wt. | Relative no. of atoms | Simplest ratio |
|---|---|---|---|---|
| Carbon | 80 | 12 | = 6.66 | = 1 |
| Hydrogen | 20 | 1 | = 20 | = 3 |
Simplest ratio of whole numbers = C : H = 1 : 3
Hence, empirical formula is CH3
Empirical formula weight = 12 + 3(1) = 15
V.D. = 15
Molecular weight = 2 x V.D. = 2 x 15
∴ Molecular formula = n[E.F.] = 2[CH3] = C2H6
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