The volume of air required for complete combustion of 20 liters of dimethylamine is ..

1. Complete combustion of dimethylamine leads to the formation of carbon dioxide, water and molecular nitrogen:

4 (CH3) 2NH + 15O2 → 8CO2 ↑ + 14H2O + 2N2 ↑;

2. The volumes of gases numerically reflect the amounts of interacting substances and reaction products, we calculate the volume of oxygen required for the combustion of amine:

V (O2) = V ((CH3) 2NH) * 15: 4 = 20 * 15: 4 = 75 l;

3. The volume fraction of oxygen in the air mixture is 21%, we calculate the volume of air:

V (air) = V (O2): ϕ (O2) = 75: 0.21 = 357.14 liters.

Answer: 357.14 liters.