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Question
The following experiment was performed in order to determine the formula of a hydrocarbon. The hydrocarbon X is purified by fractional distillation.
0.145 g of X was heated with dry copper (II) oxide and 224 cm3 of carbon dioxide was collected at S.T.P.
Calculate the empirical formula of X by the following step:
Deduce the ratio of atoms of each element in X (empirical formula).
Solution
Percentage of C in X, = `0.12/0.145 xx 100` = 82.7%
Percentage of H in X, = `0.025/0.145 xx 100` = 17.3%
| Element | %age | Atomic weight | Atomic ratio | Simplest ratio | Simplest whole number ratio |
| C | 82.7 | 12 | `82.7/12` = 6.89 | `6.89/6.89` = 1 | 1 × 2 = 2 |
| H | 17.3 | 1 | `17.3/1` = 17.3 | `17.3/6.89` = 2.5 | 2.5 × 2 = 5 |
∴ Empirical formula of X = C2H5
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The following experiment was performed in order to determine the formula of a hydrocarbon. The hydrocarbon X is purified by fractional distillation.
0.145 g of X was heated with dry copper (II) oxide and 224 cm3 of carbon dioxide was collected at S.T.P.
Calculate the empirical formula of X by the following step:
Calculate the mass of carbon contained in this quantity of carbon dioxide and thus the mass of carbon in sample X.
The following experiment was performed in order to determine the formula of a hydrocarbon. The hydrocarbon X is purified by fractional distillation.
0.145 g of X was heated with dry copper (II) oxide and 224 cm3 of carbon dioxide was collected at S.T.P.
Calculate the empirical formula of X by the following step:
Calculate the mass of hydrogen in sample X.
