Cu2+ (aq) + I- (aq)-> Cul (s) + I2 (s)

I'm having troubles balancing it. The correct coefficients are 2 4 2 1. Can someone guide me through this one please? It's a SAT problem.

Follow these steps

write it in two half reactions

balance atoms (other than H and O )

in your case there are no H and O

so just balance the charges by adding electrons

equalize the number of electrons lost or gained.

add two balance half reactions

Try these steps