Question

The formula unit for the ionic compound, iron(III) fluoride, consists of which of the following?
? 2 Fe3+ ions and 3 F2- ions
? 1 Fe2+ ion and 2 F- ions
? 1 Fe2+ ion and 1 F2- ion
? 1 Fe+ ion and 1 F- ion
? 1 Fe3+ ion and 3 F- ions

Answer 1

The formula unit for iron(III) fluoride is composed of 1 Fe³⁺ ion and 3 F⁻ ions. This is because iron(III) indicates that iron has a +3 charge, and fluoride ions (F⁻) have a -1 charge. To balance the charges, one Fe³⁺ ion will combine with three F⁻ ions.

Therefore, the correct answer is:

**1 Fe³⁺ ion and 3 F⁻ ions**.