Consider the balanced equation for the following reaction:

3CuO (s) + 2NH3 (g) → 3H2O (l) + 3Cu (s) + N2 (g)

If CuO is present in excess, determine the amount of NH3 needed to produce 2.94 moles of H2O.

The amount of ammonia needed is 33.3 g

Therefore, we can also say 1.96 moles of NH₃

Explanation:

The reaction is: 3CuO (s) + 2NH₃ (g) → 3H₂O (l) + 3Cu (s) + N₂ (g)

If we see stoichiometry, 3 moles of water can be produced by 2 moles of NH₃. We propose this rule of three:

3 moles of water can be produced by 2 mole of ammonia

Then, 2.94 moles of water, must be produced by (2.94. 2) / 3 = 1.96 moles of NH₃

If we convert the moles to mass. 1.96 mol. 17 g / 1mol = 33.3 g