# When 9 grams of oxygen-free substance is burned, 12.6 g of water and 2.24 liters of nitrogen and carbon dioxide

When 9 grams of oxygen-free substance is burned, 12.6 g of water and 2.24 liters of nitrogen and carbon dioxide are formed. This substance can be obtained by the reduction of a nitro compound with hydrogen in the presence of a catalyst. 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 * 2.24 / 22.4 = 0.2 mol
n (H) = n (H2O) * 2 = (12.6 / 18) * 2 = 1.4 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 0.2 mol
Find the molar mass of the desired compound: M = m / n = 9 / 0.2 = 45
The substance contains 1 nitrogen atom, 7 hydrogen atoms. Let’s subtract from 45 the relative atomic mass of 1 nitrogen atom and 7 hydrogen atoms: 45 – 14 – 7 = 24. The atomic mass of carbon 12. That is, there are 2 carbon atoms in the molecule of the desired substance
The answer is C2H7N – nitroethane Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.