a)
\(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
\(Al_2O_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2O\)
\(Al_2\left(SO_4\right)_3+6NaOH\rightarrow2Al\left(OH\right)_3\downarrow+3Na_2SO_4\)
\(2Al\left(OH\right)_3\underrightarrow{t^o}Al_2O_3+3H_2O\)
\(Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\)
b)
\(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)
\(FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3\downarrow+3NaCl\)
\(2Fe\left(OH\right)_3\underrightarrow{t^o}Fe_2O_3+3H_2O\)
\(Fe_2O_3+3H_2\underrightarrow{t^o}2Fe+3H_2O\)
c)
\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)
\(FeSO_4+2NaOH\rightarrow Fe\left(OH\right)_2\downarrow+Na_2SO_4\)
\(Fe\left(OH\right)_2+2HCl\rightarrow FeCl_2+2H_2O\)
\(FeCl_2+2AgNO_3\rightarrow Fe\left(NO_3\right)_2+2AgCl\)
d)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(FeCl_2+2NaOH\rightarrow Fe\left(OH\right)_2\downarrow+2NaCl\)
\(Fe\left(OH\right)_2\underrightarrow{t^o}FeO+H_2O\)
\(FeO+H_2\underrightarrow{t^o}Fe+H_2O\)
