How much O2 will be used for combustion of 40L of methane? How much carbon dioxide will this make?

Let’s write down the solution to the problem:
1. Let’s compose an equation, select the coefficients:
CH4 = 2O2 = CO2 + 2H2O + Q – the reaction of methane combustion is accompanied by the release of carbon dioxide, water and heat;
2. Let’s calculate the amount of moles of methane, oxygen:
1 mol of gas at normal level – 22.4 liters.
X mol (CH4) – 40 liters. hence, X mol (CH4) = 1 * 40 / 22.4 = 1.785 mol;
1.785 mol (CH4) – X mol (O2);
-1 mol – 2 mol from here, X mol (O2) = 1.785 * 2/1 = 3.57 mol;
According to the equation, the amount of moles of methane and carbon dioxide is equal to 1 mol, which means that Y (CO2) = 1.785 mol.
3. Find the volume of O2, CO2:
V (CO2) = 1.785 * 22.4 = 39.98 liters.
V (O2) = 3.57 * 22.4 = 79.96 liters.
Answer: the volume of oxygen is 79.96 liters, the volume of CO2 is 39.98 liters.