a)
$Fe + 2HCl \to FeCl_2 + H_2$
Theo PTHH :
$n_{Fe\ pư} = n_{H_2} = \dfrac{33,6}{22,4} = 1,5(mol)$
$m_{Fe\ pư} = 1,5.56 = 84(gam)$
b)
$n_{HCl} = 2n_{H_2} = 3(mol) \Rightarrow C_{M_{HCl}} = \dfrac{3}{0,5} = 6M$
Fe+2HCl->FeCl2+H2
1,5----3----------------1,5 mol
n H2=33,6\22,4=1,5 mol
=>m Fe=1,5.56=84g
=>Cm HCl=3\0,5=6M