Question

2C2H6(g) + 7O2(g) = 4CO2(g) + 6H2O(g) How many L of oxygen gas is needed to produce 18.0 L of CO2

Answer 1

I guess that 22.909 L

Answer 2

Use the coefficients.
18 L CO2 x (7 mols O2/4 mols CO2) = 18 x 7/4 = ?
The answer is NOT 22.909.