Determine the volume of hydrogen that will be released during the interaction of a 40 g

Determine the volume of hydrogen that will be released during the interaction of a 40 g sample of magnesium containing 4% impurities with a hydrochloric acid solution.

Given:
m mixture (Mg) = 40 g
w approx. (Mg) = 4%
To find:
V (H2)
Decision:
Mg + 2HCl = MgCl2 + H2
w is clean. islands (Mg) = 100% -4% = 96% = 0.96
m in islands (Mg) = m mixture * w pure. in-va = 40 g * 0.96 = 38.4 g
n (Mg) = m / M = 38.4 g / 24 g / mol = 1.6 mol
n (Mg): n (H2) = 1: 1
n (H2) = 1.6 mol
V (H2) = n * Vm = 1.6 mol * 22.4 L / mol = 35.84 L
Answer: 35.84 L