Question

Question #ac64e

Answer 1

Here's what I got.

Explanation:

Interestingly enough, the name sodium phosphate is actually used to describe a family of salts that contain sodium cations and phosphate anions in various ratios.

My guess is that you are supposed to treat "sodium phosphate" as trisodium phosphate, `"Na"_3"PO"_4`.

The idea here is that a formula unit of sodium phosphate, `"Na"_3"PO"_4`, contains

• three sodium cations, `3 xx "Na"^(+)`
• one phosphate anion, `1 xx "PO"_4^(3-)`

This, of course, implies that `1` mole of sodium phosphate will contain `3` moles of sodium cations and `1` mole of phosphate anions.

In other words, you have

• `"no. of moles of Na"^(+) = 3 xx "no. of moles of Na"_3"PO"_4`
• `"no. of moles of PO"_4^(3-) = "no. of moles of Na"_3"PO"_4`

Since you know that your sample contains `0.500` moles of sodium phosphate, you can say that it contains `1.50` moles of sodium cations and `0.500` moles of phosphate anions.