$a\bigg)$
$Cl_2+H_2O\leftrightharpoons HCl+HClO$
$CH_4+Cl_2\xrightarrow{ánh\, sáng}CH_3Cl+HCl$
$CH_3Cl+Cl_2\xrightarrow{ánh\, sáng}CH_2Cl_2+HCl$
$CH_2Cl_2+Cl_2\xrightarrow{ánh\, sáng}CHCl_3+HCl$
$CHCl_3+Cl_2\xrightarrow{ánh\, sáng}CCl_4+HCl$
$b\bigg)$
- Chất khử:
$2KMnO_4+16HCl\to 2KCl+2MnCl_2+5Cl_2+8H_2O$
- Chất oxi hóa:
$Fe+2HCl\to FeCl_2+H_2$
- Chất trao đổi:
$AgNO_3+HCl\to AgCl\downarrow+NaNO_3$