When aluminum is placed in concentrated hydrochloric acid hydrogen gas is produced. what mass?

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