The hydrogen vapor density of the hydrocarbon is 39. Find the molecular formula if the mass fractions of the elements are: carbon = 92.3%, hydrogen = 7.7%
Let’s write down the data on the condition of the problem:
1. Given: CxNu – hydrocarbon;
D (H2) = 39;
M (H2) = 2 g / mol;
W (C) = 92.3%
W (H) = 7.7%
Determine the molecular formula.
2. Calculate the molar mass:
M (CxHy) = M (H2) * D (H2) = 2 * 39 = 78 g / mol.
3. Find the number of moles of carbon, hydrogen:
Y (C) = m / M = 92.3 / 12 = 7.7;
Y (H) = m / M = 7.7 / 1 = 7.7.
4. Ratio: X: Y = 7, 7: 7, 7 = 1: 1;
Simplest formula: CH
Molecular Formula: C6H6;
M (C6H6) = 78 g / mol.
Answer: C6H6 – benzene belongs to the class of arenes.
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