Find the mass of magnesium reacted with hydrochloric acid if 6.72 liters of hydrogen are released

To solve, we write the equation:
Mg + 2HCl = MgCl2 + H2 – substitution reaction, hydrogen is released;
Let’s make the calculations:
M (Mg) = 24.3 g / mol; M (H2) = 2 g / mol;
Determine the number of moles of hydrogen:
1 mol of gas at normal level – 22.4 liters.
X mol (H2) – 6.72 L from here, X mol (H2) = 1 * 6.72 / 22.4 = 0.3 mol;
Y (Mg) = 0.3 mol, since according to the reaction equation, the number of moles of hydrogen and magnesium is equal to 1 mol.
We calculate the mass of magnesium by the formula:
m (Mg) = Y * M = 0.3 * 24.3 = 7.29 g.
Answer: The mass of magnesium is 7.29 g.