Question

Относительная плотность паров углеводорода по воздуху равна 3.31 , а массовая доля водорода в нем равна 12,5%. Опоеделите молекулярную формулу углеводорода

Answer 1

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Answer 2

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Answer 3

Molecular Formula of Hydrocarbon with Relative Density and Hydrogen Mass Fraction

The relative density of the hydrocarbon vapor is given as 3.31, and the mass fraction of hydrogen in it is 12.5%. We can use this information to determine the molecular formula of the hydrocarbon.

First, let's calculate the number of carbon and hydrogen atoms in the molecule using the given data.

The relative density of the hydrocarbon vapor is 3.31, and the mass fraction of hydrogen is 12.5%. We can use this information to calculate the molecular formula of the hydrocarbon.

The molecular formula can be calculated using the following steps:

1. Calculate the number of carbon atoms: - The relative density of the hydrocarbon vapor is 3.31. - Using the formula: \( D(\text{hydrocarbon}) = \frac{M_r(\text{hydrocarbon})}{M_r(\text{air})} \), where \( M_r \) represents the molar mass. - From the given data, we can calculate the molar mass of the hydrocarbon.

**Source* provides a formula for calculating the molar mass: ``` D (hydrocarbon) = Mr (hydrocarbon) / Mr (air) Mr (hydrocarbon) = D (hydrocarbon) * Mr (air) Mr (air) = 29 Mr (hydrocarbon) = 3.45 * 29 = 100 ```

Using the molar mass, we can calculate the number of carbon atoms: ``` N (C) = 84 : Mr (C) = 84 : 12 = 7 ```

This calculation indicates that there are 7 carbon atoms in the hydrocarbon molecule.

2. Calculate the number of hydrogen atoms: - The mass fraction of hydrogen in the hydrocarbon is 12.5%. - Using the mass fraction, we can calculate the number of hydrogen atoms.

**Source* provides the mass fraction of hydrogen: ``` 12.5% ```

Using this information, we can calculate the number of hydrogen atoms: ``` N (H) = 16 : Mr (H) = 16 : 1 = 16 ```

This calculation indicates that there are 16 hydrogen atoms in the hydrocarbon molecule.

Therefore, based on the given data, the molecular formula of the hydrocarbon can be determined as C7H16.