How do i know which charge of copper to use when i have cucl?

A copper ion can be +1 charge or a +2 charge. Copper +1 attracts one Cl- so that would be CuCl. Copper +2 attracts two Cl- so that would be CuCl2. That is how you know which charge of copper to use. When you figure out how many chlorine atoms are connected. I hope this answer helped you. 

Ibelieve y y even though i've only taken chemistry for one year

Answer(28.02g/mol);