Technical aluminum weighing 17 grams, containing 7% impurities, was dissolved in an excess of hydrochloric acid

Technical aluminum weighing 17 grams, containing 7% impurities, was dissolved in an excess of hydrochloric acid. Calculate the amount of hydrogen released.

Given:
m tech. (Al) = 17 g
ω approx. = 7%

To find:
V (H2) -?

Decision:
1) Write the reaction equations:
2Al + 6HCl => 2AlCl3 + 3H2 ↑;
2) Calculate the mass fraction of Al:
ω (Al) = 100% – ω approx. = 100% – 7% = 93%;
3) Calculate the mass of pure Al:
m clean (Al) = ω (Al) * m tech. (Al) / 100% = 93% * 17/100% = 15.81%;
4) Calculate the amount of Al substance:
n (Al) = m pure. (Al) / M (Al) = 15.81 / 27 = 0.59 mol;
5) Determine the amount of substance H2:
n (H2) = n (Al) * 3/2 = 0.59 * 3/2 = 0.89 mol;
6) Calculate the volume H2:
V (H2) = n (H2) * Vm = 0.89 * 22.4 = 19.9 liters.

Answer: The volume of H2 is 19.9 liters.