Question

What is the total mass of copper consumed when 16.0 moles of water are produced?

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

Answer 1

762.55 g.

Step-by-step explanation:

• For the balanced reaction:

3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O.

It is clear that 3 mol of Cu reacts with 8 mol of HNO₃ to produce 3 mol of Cu(NO₃)₂, 2 mol of NO, and 4 mol of H₂O.

• We need to calculate the no. of moles of copper consumed when 16.0 moles of water are produced:

Using cross multiplication:

3 mol of Cu produce → 4 mol of H₂O, from stichiometry.

??? mol of Cu produce → 16 mol of H₂O.

∴ no. of moles of Cu needed = (3 mol)(16 mol)/(4 mol) = 12 mol.

• Now, we can get the mass of Cu needed:

∴ mass of Cu = (no. of moles)(atomic mass of Cu) = (12 mol)(63.546 g/mol) = 762.55 g.