Question

how many liters of CO2 and water vapor are produced by burning .3 liters of C2H2 (Acetylene) with .75 liters of O2? The balanced equation is:

2C2H2 + 5O2 = 2 H2O + 4CO2

Answer 1

All are gases therefore, you may use as a shortcut that the L is directly the same as mols.
0.3L C2H2 x (2 H2O/2 C2H2) = ?L H2O produced.
0.3L C2H2 x (4 mols CO2/2 mols C2H2) = ? L CO2 produced.

0.3 L C2H2 x (5 mols O2/2 mols C2H2) = ? mols O2 used.