The combustion of 2 liters of alcohol vapor required 9 liters of oxygen. Establish the structure of the alcohol molecule

The combustion of 2 liters of alcohol vapor required 9 liters of oxygen. Establish the structure of the alcohol molecule if it is known that it forms a compound upon oxidation that gives a silver mirror reaction.

Given:
V (alcohol) = 2 l
V (O2) = 9 l

Find:
alcohol – ?

1) Monohydric alcohols have the general formula:
CnH2n + 2O;
2) Write the equation of a chemical reaction, guided by the Gay-Lussac law (the law of volumetric ratios):
2CnH2n + 2O + 9O2 => 2nCO2 + (2n + 2) H2O;
3) Make an equation and solve it (by the number of oxygen atoms):
2 * 1 + 9 * 2 = 2n * 2 + (2n + 2) * 1;
2 + 18 = 4n + 2n + 2;
6n = 18;
n = 3;
4) Unknown substance – C3H8O – C3H7OH – propanol-1.

Answer: Unknown substance – C3H7OH – propanol-1.