Aluminum was dissolved in hot sodium hydroxide solution to form sodium

Aluminum was dissolved in hot sodium hydroxide solution to form sodium tetrahydroxoaluminate. At the same time, 13.44 liters of gas were released. Determine the mass of dissolved aluminum.

The reaction of obtaining sodium tetrahydroxoaluminate as a result of the interaction of an aqueous solution of alkali with aluminum. Gas is evolved – hydrogen.
2Al + 2NaOH + 6H2O = 2Na [Al (OH) 4] + 3H2.
Determine the amount of moles of released hydrogen.
n (H2) = V / Vm = 13.44 L / 22.4 mol / L = 0.6 mol.
The number of moles of aluminum, taking into account the stoichiometric coefficients of the reaction.
2 Al – 3 H2, x mol Al – 0.6 mol H2.
n (Al) = 2 • 0.6 mol / 3 = 0.4 mol.
The mass of aluminum is.
m (Al) = n • Mr = 0.4 mol • 27 g / mol = 10.8 g.