$NaCl+ H_2SO_4 \buildrel{{t^o}}\over\longrightarrow NaHSO_4+ HCl$
$2HCl \buildrel{{đpdd}}\over\longrightarrow 2H_2+ O_2$
$2Fe+ 3Cl_2 \buildrel{{t^o}}\over\longrightarrow 2FeCl_3$
$FeCl_3+ 3AgNO_3 \rightarrow 3AgCl+ Fe(NO_3)_3$
$2AgCl \buildrel{{t^o}}\over\longrightarrow 2Ag+ Cl_2$
$Cl_2+ 2NaBr \rightarrow 2NaCl+ Br_2$
$Br_2+ 2KI \rightarrow 2KBr+ I_2$
