2Al+3Cl2=2AlCl3

Question

calculate the amount(number) of excess reagen units remaining when 4.03x10^23 Al atoms and 6.42x10^23 Cl2 molecules react?

please help!!!!! thanks

Answer 1

For each Al, one needs 1.5 Cl2

So, one needs 1.5*4.03E23 or 6.045E23 Cl2.
Thus, there is an excess of Cl2.