Question

What compound forms between `Fe^(3+)` and `SO_4^(2-)`? What is its name?

Answer 1

Iron(III) sulfate

Explanation:

The first thing to note here is that the compound that contains the `"Fe"^(3+)` cations and the `"SO"_4^(2-)` anions must be neutral.

This means that the overall positive charge coming from the cations must be balanced by the overall negative charge coming from the anions.

In this case, you will need two `"Fe"^(3+)` cations for every three `"SO"_4^(2-)` anions to form a neutral compound.

`color(red)(2)"Fe"^color(blue)(3+) + color(blue)(3)"SO"_ 4^color(red)(2-) -> "Fe"_ color(red)(2)("SO"_ 4)_ color(blue)(3)`

Now, in order to name this compound, you must use the fact that iron is a transition metal, which implies that it can form more than one cation.

In order to show that the iron cation carries a `3+` charge, you must use Roman numerals. In this case, you will have

`"Fe"^(3+) ->` the iron(III) cation

The (III) Roman numeral shows that the cation carries a `3+` charge. The anion is called sulfate, which means that the resulting ionic compound will be

`"Fe"_ 2("SO"_ 4)_ 3 ->` iron(III) sulfate