What volume of hydrogen sulfide is formed by the interaction of 880 g of technical iron (II) sulfide, containing 10% impurities

What volume of hydrogen sulfide is formed by the interaction of 880 g of technical iron (II) sulfide, containing 10% impurities, with a solution containing 10 mol of hydrochloric acid.

1) Let’s compose the reaction equation:
FeS + 2HCl = FeCl2 + H2S ↑
2) Calculate the mass and amount of the FeS substance:
ω (FeS) = 100 – ω (impurities) = 100-10 = 90%
m (FeS) = (m (solution)) ∙ ω (FeS) / 100% = 880 ∙ 90/100 = 792 g.
n (FeS) = m (FeS) / M (FeS) = 792/88 = 9 mol.
3) Determine the volume of released gas:
According to the reaction equation:
n (H2S) = n (FeS) = 2n (HCl)
FeS is in excess, HCl will react completely and 5 mol of H2S is formed
V (H2S) = n (H2S) ∙ Vm = 5 • 22.4 = 112 liters.
Answer: 112 liters.