Question

75.0 moles of Copper metal reacts with 70.0 moles of chlorine gas to produce copper (II) chloride.

Which reactant is the excess reactant?

Answer 1

copper

Step-by-step explanation:

First, write down the reaction and notice the ratio of moles of which the reactants react.

the equation (i'm too lazy to write states of matter and since it doesnt matter in this problem i'm not going to. it is balanced, however) is:
Cl2 + Cu -> CuCl2

as you can see, one mole of chlorine gas reacts with one mole of copper.

since we have 75 moles of copper but only 70 moles of chlorine gas, after everything has been reacted we would expect 5 moles of copper to be left over. so, copper is the the reactant which is in excess