The formula unit for the ionic compound, chromium(II) chloride, consists of which of the following?

Question

? 1 Cr2+ ion and 1 Cl2- ion
? 1 Cr+ ion and 1 Cl- ion
? 1 Cr2- ion and 2 Cl+ ions
? 1 Cr2+ ion and 2 Cl- ions
? 1 Cr3+ ion and 3 Cl- ions

Answer 1

The correct formula unit for the ionic compound chromium(II) chloride is:

1 Cr²⁺ ion and 2 Cl⁻ ions

So, the answer is:

? 1 Cr²⁺ ion and 2 Cl⁻ ions

In this case, the chromium ion has a +2 charge (Cr²⁺) and each chloride ion has a -1 charge (Cl⁻). Therefore, it takes two chloride ions to balance the charge of one chromium ion, resulting in the formula CrCl₂.