How much hydrogen is formed by the interaction of 80 g of calcium containing 20%

How much hydrogen is formed by the interaction of 80 g of calcium containing 20% of impurities with the required amount of hydrochloric acid.

We write down the equation of reactions.
Ca + 2 HCl = CaCl2 + H2.
We find the mass of impurities.
m (impurities) = 80 × 0.2 = 16 g.
Next, we find the mass of pure calcium. We write down the solution.
m (Ca) = 80 g – 16 g = 64 g.
Next, we find the mass of hydrogen according to the reaction equation.
M (Ca) = 40 g / mol.
M (H2) = 1 × 2 = 2 g / mol.
64 g Ca – x g H2.
40 g / mol Ca – 2 g / mol H2.
Find the unknown value of x.
X = 64 × 2 ÷ 40 = 3.2 g H2.
Next, we find the volume of hydrogen.
n = m / M.
n = V / Vm.
m / M = V / Vm.
V = m × Vm / M = 3.2 × 22.4 ÷ 2 = 35.84 l H2.
Answer: V (H2) = 35.84 liters.