a)
(1): \(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
(2) \(Al_2O_3+6HCl->2AlCl_3+3H_2O\)
3) \(AlCl_3+3NaOH->Al\left(OH\right)_3\downarrow+3NaCl\)
4) \(2Al\left(OH\right)_3\underrightarrow{t^o}Al_2O_3+3H_2O\)
5) \(Al_2O_3+3H_2SO_4->Al_2\left(SO_4\right)_3+3H_2O\)
6) \(Al_2\left(SO_4\right)_3+6NaOH->3Na_2SO_4+2Al\left(OH\right)_3\downarrow\)
b)
1) \(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)
2) \(FeCl_3+3NaOH->Fe\left(OH\right)_3\downarrow+3NaCl\)
3) \(2Fe\left(OH\right)_3\underrightarrow{t^o}Fe_2O_3+3H_2O\)
4) \(Fe_2O_3+3CO\underrightarrow{t^o}2Fe+3CO_2\)
5) \(Fe+2HCl->FeCl_2+H_2\uparrow\)
6) \(FeCl_2+2NaOH->Fe\left(OH\right)_2\downarrow+2NaCl\)
7) \(Fe\left(OH\right)_2+H_2SO_4->FeSO_4+2H_2O\)
