What volume of hydrogen can be obtained by reacting magnesium with a solution of phosphoric

What volume of hydrogen can be obtained by reacting magnesium with a solution of phosphoric acid with an amount of 0.5 mol?

The reaction of interaction of magnesium with phosphoric acid is as follows:
3Mg + 2H3PO4 = Mg3 (PO4) 2 + 3H2.
It can be seen from it that when 2 moles of acid enter into the reaction, 3 moles of hydrogen are obtained.
Thus, the volume of hydrogen is:
0.5 mol * (3: 2) * 22.4 l / mol = 0.75 * 22.4 = 16.8 l.