JAMB - Chemistry (2024 - No. 21)

The table above shows the formulae of some ions. In which of these compounds is the formula not correct?

Aluminiumtetraoxosulphate(VI), Al\(_2\)(SO\(_4\))\(_3\)

Calciumtrioxonitrate(V), Ca(NO\(_3\))\(_2\)

Iron(III)bromide, Fe\(_3\)Br

Potassiumsulphide, K\(_2\)S

Iron(III)bromide is the correct answer because Fe has a valency of +3 while Br has a valency of -1,

In the bid to form compounds, they bond together and exchange their valency.

⇒ Fe takes the valency of Br which is 1 while Br takes the valency of Fe which is 3.

Therefore, the formula for the compound formed should be FeBr\(_3\) and not Fe\(_3\)Br