What is the correct name for FePO4 ?
a)iron(III) phosphate
b)iron(II) phosphite
c)iron(III) phosphide
d)iron(I) phosphate
e)iron(III) phosphite
The Correct Answer and Explanation is :
The correct name for FePO₄ is:
a) iron(III) phosphate.
Explanation
- Understanding FePO₄:
- Fe is the symbol for iron.
- PO₄ is the formula for the phosphate ion, which carries a -3 charge.
- Together, FePO₄ is an ionic compound made of iron and phosphate ions.
- Iron Oxidation State:
- Iron can exhibit multiple oxidation states, including +2 and +3.
- In FePO₄, phosphate has a -3 charge. For the compound to be electrically neutral, the iron must balance this charge.
- A single Fe ion must have a +3 charge to balance the -3 charge of the phosphate ion.
- Naming Rules for Ionic Compounds:
- The cation (positive ion) is named first, followed by the anion (negative ion).
- For metals like iron that can have multiple oxidation states, the oxidation state is indicated in Roman numerals in parentheses.
- The name of the anion is derived from its root name, with “-ate” or “-ite” depending on the ion type.
- Analyzing the Options:
- a) iron(III) phosphate: Correct. The Fe³⁺ ion is paired with the phosphate ion (PO₄³⁻).
- b) iron(II) phosphite: Incorrect. This suggests Fe²⁺ and the phosphite ion (PO₃³⁻), which is a different compound.
- c) iron(III) phosphide: Incorrect. Phosphide refers to the ion P³⁻, not PO₄³⁻.
- d) iron(I) phosphate: Incorrect. Iron(I) (Fe⁺) does not exist in stable compounds like this.
- e) iron(III) phosphite: Incorrect. Phosphite (PO₃³⁻) is not present here.
Thus, FePO₄ is correctly named iron(III) phosphate because it contains Fe³⁺ and PO₄³⁻.