Question

What is the charge of phosphate in AlPO4?

Answer 1

The charge of phosphate : 3-

Further explanation

Oxidation is an increase in oxidation number, while reduction is a reduction in oxidation number.

The formula for determining Oxidation Numbers in general:

1. Single element atomic oxidation number = 0.

Group IA (Li, Na, K, Rb, Cs, and Fr): +1

Group IIA (Be, Mg, Ca, Sr and Ba): +2

Group IIIA(Al, B) : +3

H in compound = +1, except metal hydride compounds (Hydrogen which binds to groups IA or IIA) oxidation number H = -1, for example, LiH, MgH₂, etc.

2. Oxidation number O in compound = -2, except OF2 = + 2 and in peroxide (Na₂O₂, BaO₂) = -1 and superoxide, for example KO₂ = -1/2.

3 The oxidation number in an uncharged compound = 0,

Total oxidation number in ion = ion charge, Example NO₃⁻ = -1

Compound AlPO₄ :

The oxidation number in an uncharged compound = 0

Since the charge of Al as group 3A (or group 13) is +3, while the AlPO₄ compound is a polyatomic compound (consisting of polyatomic ions PO₄ and Al), the PO₄ charge:

charge Al + charge PO₄ = 0

+ 3 + charge PO₄ = 0

charge PO₄ = -3