Question

If 2.5 L N2 reacts with 7 L H2, what is the theoretical yield (in liters) of NH3? Assume that the volumes of reactants and products are measured at the same temperature and pressure.

Answer 1

This is a limiting reagent problem. I know that because a value is given for BOTH reactants. In this case, where all of the materials are gases, one may take a shortcut and use volumes as moles.
Using the coefficients in the balanced equation, convert 2.5 L N2 to L NH3. Do the same for 7.0 L H2. The answers will not be the same; the correct answer in limiting reagent problems is ALWAYS the smaller value. The answer you obtain will be the theoretical yield.