What volume of reactant, measured at STP, is left over in liters? Assume the reaction goes to completion. N₂ (g) + 3 H₂ (g) → 2 NH₃ (g)

Question

The Haber Process synthesizes ammonia at elevated temperatures and pressures. Suppose you combine 1583 L of nitrogen gas and 4471 L of hydrogen gas at STP, heat the mixture to run the reaction, then separate the ammonia from the reaction mixture.

Answer 1

At the same pressure and temperature, the volume of a gas is proportional to the number of moles of the gas, so the volume can be used in place of moles in the reaction calculations.

The number of liters of ammonia produced from hydrogen is 2/3 x 4471 L = 2981 L.

The number of liters of ammonia produced from nitrogen is 2 x 1583 L = 3166 L.

As the liters of ammonia produced is less for hydrogen, it is the limiting reactant. As the reaction shows that the volume of nitrogen necessary is 1/3 the volume of hydrogen, the volume of nitrogen used is 1490 L.

The volume of nitrogen left over is 1583 - 1490 = 93 L.