If 35.0 g of ammonia (NH₃) are produced, how many grams of nitrogen are required to make these 35.0 grams of NH₃ according to the unbalanced equation N2 + H2 = NH3

Answer 1

Let's start by balancing this reaction.

N₂ + 3 H₂ ---> 2 NH₃

Now there are 2 N, 6 H on each side of the equation.

Let's consider the value they gave us, 35.0 grams of ammonia. They would like to know the grams of nitrogen gas required to make 35 grams of ammonia. Remember that the relationship described by the balanced equation describes the stoichiometry of the reaction. This means we need to be able to relate the number of moles to the number of grams given. The way we can relate those is by the molar mass, which units are grams/mole.

NH3 molar mass = 14 + 3(1) = 17 g/mol

N2 molar mass = (2)14 = 28 g/mol

Let's figure out the number of moles that corresponds to 35.0 grams of ammonia.

35.0 g / 17 g/mol = 2.06 mol

Based on the balanced equation, there are 2 moles of ammonia produced for every 1 mole of nitrogen gas. This means the number of moles for nitrogen must be 2.06/2 = 1.03 moles.

Now, to find the number of grams of nitrogen, multiply the moles by the molar mass.

1.03 mol * 28 g/mol = 28.8 g. This answer is 3 sig figs, since 3 sig figs were given in the problem.