Question

Ammonia (NH3) clouds are present around some planets. Calculate the number of grams of ammonia produced by the reaction of 5.4 g of hydrogen with an excess of nitrogen
N2 + 3 H2 -> 2 NH3

Answer 1

30.6 g of ammonia are produced.

Answer:

given

mass of hydrogen =5.4 gram

mass of NH3=?

we have

3 moles of H2=2 moles of NH3

3×2g of H2=2×(14+3) g of NH3

6 g of H2=34 g of NH3

5.4 g of H2=34×5.4/6=30.6 g of NH3

Answer 2

Answer:

30.4 g. NH3

Explanation:

This problem tells us that the hydrogen (H2) is the limiting reactant, as there is "an excess of nitrogen." Using stoichiometry (the relationship between the various species of the equation), we can see that for every 3 moles of H2 consumed, 2 moles of NH3 are produced.

But before we can use that relationship to find the number of grams of ammonia produced, we need to convert the given grams of hydrogen into moles:

5.4 g x [1 mol H2/(1.008x2 g.)] = 2.67857 mol H2 (not using significant figures yet; want to be as accurate as possible)

Now, we can use the relationship between H2 and NH3.

2.67857 mol H2 x (2 mol NH3/3 mol H2) = 1.7857 mol NH3

Now, we have the number of moles of ammonia produced, but the answer asks us for grams. Use the molar mass of ammonia to convert.

1.7857 mol NH3 x 17.034 g. NH3/mol NH3 = 30.4 g. NH3 (used a default # of 3 sig figs)