how many gramss of HCl to dassolve 2,5 g
Fe in a lock and how much H_2 would be produced
Fe(s)+2HCl(aq)-FeCl_2(aq)+H_2(g)
Fe + 2HCl -> FeCl2 + H2
2.5g Fe = 0.0447 moles Fe
so, 0.0895 moles of HCl will be used. That is 3.26 g HCl
you also get 0.0447 moles H2 = 0.0895g H2.