What is the correct formula unit for the ionic compound, copper(II) sulfide?

? CuS2
? Cu2S
? Cu2S2
? CoS
? CuS

1 answer

The correct formula unit for the ionic compound copper(II) sulfide is CuS.

Copper(II) indicates that copper has a +2 oxidation state, while sulfide has a -2 oxidation state. To balance these charges, one copper ion (Cu²⁺) combines with one sulfide ion (S²⁻), resulting in the formula CuS.