Question

If copper is heated in the presence of an excess of chlorine gas, how much metal is needed to make 12.20 g CuCl2?

Answer 1

To solve this problem we must write the equation of chemical reaction:

Cu + Cl₂ = CuCl₂

Then suppose that x is mass of metal needed forreaction. The molar mass of Cu is 64; the molar mass of CuCl₂ is 135.
So, we can find x:
x = (64*12.20)/135 = 5.78g