Question

When heated strongly, copper metal incorporates oxygen to form one of the copper oxides from the last problem. In one experiment, a crucible weighing 88.00 g was loaded with 10.00 g of copper metal. After 20 minutes of strong heating, the total mass was 100.52 g. How many moles of copper atoms are present in the final product?

Answer 1

1 mol of copper

Step-by-step explanation:

The mass of the oxide formed is the total mass less the crucible mass, so it is:

100.52 - 88.00 = 12.52 g

It means that 10.00 g is from copper, and 2.52 g is from oxygen. The molar mass of copper is 63.50 g/mol, and the molar mass of oxygen is 16 g/mol. The number of moles (n) is the mass divided by the molar mass:

n Cu = 10.00/63.50 = 0.158 moles

n O = 2.52/16 = 0.158 moles

So, there is the same number of moles of each element, and the product must be: CuO, which has 1 mol of copper.