When 1.86 grams of oxygen-free substance are burned, 1.26 grams of water and 224 ml of nitrogen are formed.

When 1.86 grams of oxygen-free substance are burned, 1.26 grams of water and 224 ml of nitrogen are formed. This substance can be obtained from the corresponding nitro compound. Determine the molecular and structural formula of a substance

The general formula of the substance (taking into account the method of obtaining according to the condition of the problem): CxHyN
The amount of nitrogen and hydrogen in the compound:
n (N) = 2 * n (N) = 2 * 0.224 / 22.4 = 0.02 mol
n (H) = n (H2O) * 2 = (1.26 / 18) * 2 = 0.14 mol
The ratio of nitrogen to hydrogen is 1: 7
Considering. that the molecule of the desired organic substance contains 1 nitrogen atom, then the amount of the substance of the desired compound is equal to the amount of the nitrogen substance and is equal to 0.02 mol
Find the molar mass of the desired compound: M = m / n = 1.86 / 0.02 = 93
The substance contains 1 nitrogen atom, 7 hydrogen atoms. Let’s subtract from 93 the relative atomic mass of 1 nitrogen atom and 7 hydrogen atoms: 93 – 14 – 7 = 72. The atomic mass of carbon 12. That is, there are 6 carbon atoms in the molecule of the desired substance
Answer C6H7N – nitrobenzene

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