$(1) 2Al_2O_3 \xrightarrow{đpnc} 4Al + 3O_2$
$2Al + 6HCl \to 2AlCl_3 + 3H_2$
$AlCl_3 + 3KOH \to Al(OH)_3 + 3KCl$
$(2) Fe_2O_3 + 3CO \xrightarrow{t^o} 2Fe + 3CO_2$
$2Fe  + 3Cl_2 \xrightarrow{t^o} 2FeCl_3$
$FeCl_3 + 3KOH \to Fe(OH)_3 + 3KCl$
$(3) 2Fe  + 3Cl_2 \xrightarrow{t^o} 2FeCl_3$
$FeCl_3 + 3KOH \to Fe(OH)_3 + 3KCl$
$2Fe(OH)_3 \xrightarrow{t^o} Fe_2O_3 + 3H_2O$
$Fe_2O_3 + 3CO \xrightarrow{t^o} 2Fe + 3CO_2$
$Fe + 6H_2SO_4 \to Fe_2(SO_4)_3 + 3SO_2 + 6H_2O$

\(1.a.Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\\ AlCl_3+3NaOH\rightarrow Al\left(OH\right)_3+3NaCl\\ 2Al\left(OH\right)_3-^{t^o}\rightarrow Al_2O_3+3H_2O\\ b.Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\\ FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3+3NaCl\\ 2Fe\left(OH\right)_3-^{t^o}\rightarrow Fe_2O_3+3H_2O\\ Fe_2O_3+3CO\rightarrow2Fe+3CO_2\)

2. Cho các mẫu thử vào dung dịch NaOH dư

+ Tan, có khí thoát ra: Al

\(2Al+2NaOH+2H_2O\rightarrow2NaAlO_2+3H_2\)

+ Không hiện tượng: Fe, Ag

Cho 2 mẫu thử không hiện tượng trên vào dung dịch HCl

+ Tan, có khí thoát ra: Fe

\(Fe+2HCl\rightarrow FeCl_2+H_2\)

+ Không hiện tượng : Ag

\(3.a.Fe+2HCl\rightarrow FeCl_2+H_2\\ b.n_{Fe}=n_{H_2}=0,03\left(mol\right)\\ \Rightarrow\%m_{Fe}=\dfrac{0,03.56}{8,08}.100=20,79\%;\%m_{Cu}=79,01\%\\ c.n_{HCl}=2n_{H_2}=0,06\left(mol\right)\\ \Rightarrow m_{HCl}=\dfrac{0,06.36,5}{3,65\%}=60\left(g\right)\)

\(a,2Fe+3Cl_2\xrightarrow{t^o}2FeCl_3\\ FeCl_3+3NaOH\to Fe(OH)_3\downarrow+3NaCl\\ 2Fe(OH)_3\xrightarrow{t^o}Fe_2O_3+3H_2O\\ Fe_2O_3+3CO\xrightarrow{t^o}2Fe+3CO_2\\ Fe+H_2SO_4\to FeSO_4+H_2\\ FeSO_4+BaS\to BaSO_4\downarrow+FeS\\ FeS+2HCl\to FeCl_2+H_2\\ FeCl_2+2AgNO_3\to Fe(NO_3)_2+2AgCl\downarrow\)

\(b,2Al_2O_3\xrightarrow[criolit]{đpnc}4Al+3O_2\\ 2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2\\ Al_2(SO_4)_3+6NaOH\to 2Al(OH)_3\downarrow+3Na_2SO_4\\ Al(OH)_3+3HNO_3\to Al(NO_3)_3+3H_2O\\ 2Al(NO_3)_3+3Mg\to 3Mg(NO_3)_2+2Al\\ Al+NaOH+H_2O\to NaAlO_2+\dfrac{3}{2}H_2\)

\(a,4Al+3O_2\xrightarrow[t^0]{}2Al_2O_3\\ Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\\ AlCl_3+3AgNO_3\rightarrow Al\left(NO_3\right)_3+3AgCl\\ AlCl_3+3NaOH\rightarrow Al\left(OH\right)_3+3NaCl\\ 2Al\left(OH\right)_3\xrightarrow[t^0]{}Al_2O_3+3H_2O\\ 2Al_2O_3\xrightarrow[đpnc]{criolit}4Al+3O_2\\ b,3Fe+2O_2\xrightarrow[t^0]{}Fe_3O_4\\ Fe_3O_4+8HCl\rightarrow2FeCl_3+FeCl_2+4H_2O\\ FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3+3NaCl\\ 2Fe\left(OH\right)_3\xrightarrow[t^0]{}Fe_2O_3+3H_2O\\ Fe_2O_3+3CO\xrightarrow[t^0]{}2Fe+3CO_2\)

\(c,2Fe\left(OH\right)_3+3H_2SO_4\rightarrow Fe_2\left(SO_4\right)_3+6H_2O\\ Fe_2\left(SO_4\right)_3+3BaCl_2\rightarrow2FeCl_3+3BaSO_4\\ FeCl_3+AgNO_3\rightarrow Fe\left(NO_3\right)_3+3AgCl\)

a) Các PTHH:

(1) 2 Fe +3 Cl2 -to-> 2 FeCl3

(2) FeCl3 + 3 NaOH -> Fe(OH)3 +3 NaCl

(3) 2 Fe(OH)3 -to-> Fe2O3 + 3 H2O

(4) Fe2O3 + 3 CO -to-> 2 Fe + 3 CO2

(5) Fe + 2 HCl -> FeCl2 + H2

(6) FeCl2 + 2 AgNO3 -> Fe(NO3)2 + 2 AgCl

b) Các PTHH:

(1) MnO2 + 4 HCl(đặc) -to-> MnCl2 + Cl2 + 2 H2O

(2) 3 Cl2 + 2 Fe -to-> 2 FeCl3

(3) FeCl3 + 3 NaOH -> Fe(OH)3 + 3 NaCl

(4) NaCl + H2O -ddpdddcmnx-> NaOH + 1/2 H2 + 1/2 Cl2

(5) Cl2 + Cu -to-> CuCl2

(6) CuCl2 + 2 AgNO3 -> Cu(NO3)2 + 2 AgCl

c) Các PTHH:

(1) 4 Al + 3 O2 -to-> 2 Al2O3

(2) Al2O3 + 6 HCl -> 2 AlCl3 + 3 H2O

(3) AlCl3 + 3 KOH -> 3 KCl + Al(OH)3

(4) 2 Al(OH)3 -to-> Al2O3 +3 H2O

(5) 2 Al2O3 -đpnc-> 4 Al + 3 O2

Bs đề câu a: \(Fe_2O_3\xrightarrow{(4)}Fe\)

\(a,(1)2Fe+3Cl_2\xrightarrow{t^o}2FeCl_3\\ (2)FeCl_3+3NaOH\to Fe(OH)_3\downarrow+3NaCl\\ (3)2Fe(OH)_3\xrightarrow{t^o}Fe_2O_3+3H_2O\\ (4)Fe_2O_3+3CO\xrightarrow{t^o}2Fe+3CO_2\)

\(b,(1)4Al+3O_2\xrightarrow{t^o}2Al_2O_3\\ (2)Al_2O_3+6HCl\to 2AlCl_3+3H_2\\ (3)AlCl_3+3NaOH\to Al(OH)_3\downarrow+3NaCl\\ (4)2Al(OH)_3\xrightarrow{t^o}Al_2O_3+3H_2O\)

a, \(2Al+3O_2\underrightarrow{t^o}2Al_2O_3\)

\(Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\)

\(AlCl_3+3NaOH\rightarrow3NaCl+Al\left(OH\right)_3\)

\(2Al\left(OH\right)_3\underrightarrow{t^o}Al_2O_3+3H_2O\)

\(Al_2O_3\underrightarrow{đpnc}2Al+\dfrac{3}{2}O_2\)

\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)

\(Al_2\left(SO_4\right)_3+3Mg\rightarrow3MgSO_4+2Al\)

b, \(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)

\(FeCl_3+3NaOH\rightarrow3NaCl+Fe\left(OH\right)_3\)

\(2Fe\left(OH\right)_3\underrightarrow{t^o}Fe_2O_3+3H_2O\)

\(Fe_2O_3+3H_2\underrightarrow{t^o}2Fe+3H_2O\)

\(Fe+2HCl\rightarrow FeCl_2+H_2\)

\(Mg+FeCl_2\rightarrow MgCl_2+Fe\)

\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)