Question #ac64e

1 Answer
Dec 4, 2017

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, Na3PO4.

The idea here is that a formula unit of sodium phosphate, Na3PO4, contains

  • three sodium cations, 3×Na+
  • one phosphate anion, 1×PO34

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×no. of moles of Na3PO4
  • no. of moles of PO34=no. of moles of Na3PO4

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.