Calculate the mass of oxygen that is required for complete combustion a) 5 liters of methane (CH4, gas)

Calculate the mass of oxygen that is required for complete combustion a) 5 liters of methane (CH4, gas); b) 8 liters of acetylene (C2H2, ha); c) 3 liters of hydrogen sulfide (H2S, gas) calculate the masses of the gaseous substances.

Given:
a) V (CH4) = 5 l
b) V (C2H2) = 8 l
c) V (H2S) = 3 l

To find:
m (O2) -?
m (gases) -?

a) 1) CH4 + 2O2 => CO2 + 2H2O;
2) n (CH4) = V (CH4) / Vm = 5 / 22.4 = 0.22 mol;
3) n (O2) = n (CH4) * 2 = 0.22 * 2 = 0.44 mol;
4) m (O2) = n (O2) * M (O2) = 0.44 * 32 = 14.1 g;
5) n (CO2) = n (CH4) = 0.22 mol;
6) m (CO2) = n (CO2) * M (CO2) = 0.22 * 44 = 9.7 g;

b) 1) 2C2H2 + 5O2 => 4CO2 + 2H2O;
2) n (C2H2) = V (C2H2) / Vm = 8 / 22.4 = 0.36 mol;
3) n (O2) = n (C2H2) * 5/2 = 0.36 * 5/2 = 0.9 mol;
4) m (O2) = n (O2) * M (O2) = 0.9 * 32 = 28.8 g;
5) n (CO2) = n (C2H2) * 4/2 = 0.22 * 4/2 = 0.44 mol;
6) m (CO2) = n (CO2) * M (CO2) = 0.44 * 44 = 19.4 g;

c) 1) 2H2S + 3O2 => 2SO2 + 2H2O;
2) n (H2S) = V (H2S) / Vm = 3 / 22.4 = 0.13 mol;
3) n (O2) = n (H2S) * 3/2 = 0.13 * 3/2 = 0.2 mol;
4) m (O2) = n (O2) * M (O2) = 0.2 * 32 = 6.4 g;
5) n (SO2) = n (H2S) = 0.13 mol;
6) m (SO2) = n (SO2) * M (SO2) = 0.13 * 64 = 8.3 g.

Answer: The mass of O2 is 19 g; 24 g; 5 g; CO2 – 9.7 g; 19.4 g; SO2 – 8.3 g.