Question

How many moles of Na+ ions are in 100.mL of 0.100M Na3PO4(aq)?

Answer 1

Answer:

The answer is C) 0.0300 mol

Explanation:

First you need to get the total amount of moles is dissolved in the solution. This can be obtained doing the following:

Molarity = moles of solute / liters of solution

moles of solute = molarity x liters of solution

First, the volume has to be in liters, then :

100. ml x (1 L / 1000 mL) = 0.100 L

(We then substitute)

moles of solute = 0.100 mol/L x 0.1 L = 0.0100 mol of solute (In this case Na3PO4)

Having the moles of the solute, we now need to find how many moles of Na+ ions are there.

We need the conversion factor of 3 Na+ moles per 1 mole of Na3PO4

We then find the amount of moles doing as follows:

0.0100 mol Na3PO4 x (3 mol Na+ / 1 mol Na3PO4) = 0.0300 mol Na+.