Question

Cobalt chloride (CoCl2) contains two moles of cobalt ions for every one mole of cobalt chloride.

Options:
a) CoCl2 → Co2+ + 2Cl-
b) Co2Cl → Co2+ + 2Cl-
c) CoCl2 → 2Co2+ + Cl2-
d) CoCl2 → Co2+ + Cl-

Answer 1

The correct dissociation of cobalt chloride into ions is CoCl2 → Co2+ + 2Cl-. Cobalt in CoCl2 has an oxidation state of +2, as in cobalt(II) chloride, not to be confused with cobalt(III) in other compounds like cobalt(III) oxide.

Step-by-step explanation:

The correct option for the dissociation of cobalt chloride (CoCl2) into its constituent ions is: CoCl2 → Co2+ + 2Cl-. Each cobalt ion carries a 2+ charge, and each chloride ion carries a 1- charge. Since there are two chloride ions, the total negative charge is 2-, which balances out the 2+ charge of the single cobalt ion, ensuring the compound is electrically neutral.

Additionally, it is important to note that the cobalt(II) ion (Co2+) is the cation present in CoCl2, indicating it is cobalt in its +2 oxidation state. In contrast, an oxide ion (O2-) always carries a 2- charge. Therefore, in a compound such as cobalt(III) oxide, with three oxide ions contributing a total charge of 6-, two cobalt ions would each need a charge of 3+ to balance the charge, resulting in cobalt(III).