a) $n_{HCl} = \dfrac{18,25.50\%}{36,5} = 0,25(mol)$
$Zn + 2HCl \to ZnCl_2 + H_2$
Theo PTHH :
$n_{Zn\ pư} = n_{H_2} = \dfrac{1}{2}n_{HCl} = 0,125(mol)$
$m_{Zn\ pư} = 0,125.65 = 8,125(gam)$
$V_{H_2} = 0,125.22,4 = 2,8(lít)$
b)
$m_{dd\ sau\ pư} = 8,125 + 18,25 - 0,125.2 = 26,125(gam)$
$C\%_{ZnCl_2} = \dfrac{0,125.136}{26,125}.100\% = 65,1\%$