What mass of nitrogen gas is required to react completely with 2.79 g of hydrogen gas to produce ammonia?
A) 25.8 g
B) 12.9 g
C) 78.2 g
D) 38.7 g
E) 77.4 g

Question

Quizplus · Accepted Answer

The balanced chemical equation for the production of ammonia (NH3) from nitrogen (N2) and hydrogen (H2) is N2 + 3H2 -> 2NH3. The molar mass of H2 is approximately 2 g/mol, so 2.79 g of H2 is 2.79/2 = 1.395 moles. The stoichiometry of the reaction requires 1 mole of N2 for every 3 moles of H2, so we need 1.395/3 = 0.465 moles of N2. The molar mass of N2 is approximately 28 g/mol, so the mass of N2 required is 0.465 moles * 28 g/mol = 13.02 g, which rounds to 12.9 g, making option B correct.

What Mass of Nitrogen Gas Is Required to React Completely