Question

Consider the following reaction: 4NH3(g) 7O2(g) → 4NO2(g) 6H2O(l) Consider an experiment in which you react ammonia and oxygen. At the end of the experiment, you find that you produced 27.0 g of water, and 8.52 g of ammonia is left over. Calculate the initial mass of ammonia. Assume the reaction went to completion.

Answer 1

Answer: Initial mass of ammonia: 25,537g NH3

Explanation:

• First we review the equation giving is balanced by checking the amount of each element before and after the arrow.

4NH3(g) 7O2(g) → 4NO2(g) 6H2O(l)

We have 4 Nitrogen atoms on both sides

12 Hydrogen atoms on both sides

14 Oxygen atoms on both sides

• Second we gather the information what we are going to use in our calculations.

Final Mass of H2O = 27g  and Molecular Weigth = 18,015g/mol

Left Mass of NH3 = 8,52g and Molecular Weight= 17,031 g/mol

• Third we start discoverying the amount of NH3 that reacted completely to generate 27g of H2, by using the giving equation and its respective molecular weights.

27g H2O  x  1mol H20/ 18,015 gH20  x 4mol NH3/ 6 mol H20 x 17,031g NH3 / 1mol NH3 = 17,017g NH3

17,017g NH3 were consumpted to generate 27 g of H2, however, lets remember that there is NH3 left, that must be added to finally discover the original amount

17,017g + 8,52g = 25,537g NH3