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?
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.
The ball dropped from 1m will be going the slowest. Both balls have the same acceleration, but the ball dropped off the building had more time to gain speed.
