Question

What is the molar concentration of sulfate ions in a 0.150 M `Na_2SO_4` solution?

Answer 1

`M_(SO_4^(2-))=0.150M`

Explanation:

In solution, sodium sulfate dissociates according to the following equation:

`Na_2SO_4(s)->2Na^(+)(aq)+SO_4^(2-)(aq)`

Therefore, `1mol` of `Na_2SO_4` will give `1mol` of `SO_4^(2-)` and thus, the molarity of sulfate ions will be equal to that of the sodium sulfate.

`M_(SO_4^(2-))=0.150M`

However, the molarity of sodium ions is the double of that of sodium sulfate since `1mol` of `Na_2SO_4` will give `2mol` of `Na^(+)`:

`M_(Na^(+))=0.300M`