1,
\(4HCl+MnO_2\rightarrow MnCl_2+2H_2O+Cl_2\\ 2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\\ FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3\downarrow+3NaCl\\ 2NaCl+H_2SO_4\rightarrow Na_2SO_4+2HCl\uparrow\\ CuO+2HCl\rightarrow CuCl_2+H_2O\\ CuCl_2+2AgNO_3\rightarrow2AgCl\downarrow+Cu\left(NO_3\right)_2\)
2,
\(2KMnO_4+16HCl\rightarrow2KCl+8H_2O+5Cl_2+2MnCl_2\\ Cl_2+H_2\underrightarrow{as}2HCl\\ 6HCl+Fe_2O_3\rightarrow2FeCl_3+3H_2O\\ FeCl_3+3AgNO_3\rightarrow3AgCl\downarrow+Fe\left(NO_3\right)_3\\ 2AgCl\underrightarrow{as}2Ag+Cl_2\\ Cl_2+2NaBr\rightarrow2NaCl+Br_2\\ Br_2+2NaI\rightarrow2NaBr+I_2\)
3,
2 pthh đầu giống ở 2
\(Fe+2HCl\rightarrow FeCl_2+H_2\\ FeCl_2+2AgNO_3\rightarrow2AgCl\downarrow+Fe\left(NO_3\right)_2\\ 2AgCl\underrightarrow{as}2Ag+Cl_2\)
4, 2 pthh đầu gióng ở 1
\(FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3\downarrow+3NaCl\\ 2Fe\left(OH\right)_3+3H_2SO_4\rightarrow Fe_2\left(SO_4\right)_3+6H_2O\)