I cannot answer this question if no initial mass for aluminum is given. Le'ts just suppose the initial mass of aluminum is 5 g. The reaction would be:
2 Al + 6 HCl --> 3 H₂ + 2 AlCl₃
The stoichiometric calculations are as follows:
Mass H₂ = 5 g Al * 1 mol/27 g Al * 3 mol H₂/2 mol Al * 2 g H₂/mol = 0.556 g H₂ produced
