A hydrocarbon contains 82.8% of carbon. Find it's molecular formula if it's vapour density is 29 [H = 1, C = 12]
Stoichiometry
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Question

A hydrocarbon contains 82.8% of carbon. Find it's molecular formula if it's vapour density is 29 [H = 1, C = 12]

KnowledgeBoat · Accepted Answer

Element | % composition | At. wt. |Relative no. of atoms| Simplest ratio --------|---------------|---------|----------------------|---- Carbon | 82.8 | 12 | = 6.9 | = 1 Hydrogen | 100 - 82.8 = 17.2 | 1 | = 17.2 | = 2.5 C : H = 1 : 2.5 = 1 : = 2 : 5 Simplest ratio of whole numbers = 2 : 5 Hence, empirical formula is C₂H₅ Empirical formula weight = 2(12) + 5(1) = 24 + 5 = 29 Vapour density (V.D.) = 29 Molecular weight = 2 x V.D. = 2 x 29 = 58 Molecular formula = n[E.F.] = 2[C₂H₅] = C₄H₁₀ Hence, Molecular formula = C₄H₁₀

Chemistry

A hydrocarbon contains 82.8% of carbon. Find it's molecular formula if it's vapour density is 29 [H = 1, C = 12]

Stoichiometry

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