Some Basic Concepts of Chemistry

Some Basic Concepts of Chemistry

Question

A gaseous hydrocarbon gives upon combustion 0.72 g of water and 3.08 g of CO2.The empirical formula of the hydrocarbon is 

  • C2H4

  • C3H4

  • C6H5

  • C7H8

Answer

D.

C7H8

18 g H2O contains 2gH
therefore, 0.72 g H2O contains 0.08 g H
44 g CO2 contains 12 g C
therefore, 3.08 g CO2 contains 0.84 g C
∴ C:H = 0.84/12: 0.08/1
 + 0.07 : 0.08 = 7:8
∴Empirical formula = C7H8

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