Ta có: \(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)

PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)

a, \(n_{H_2}=n_{Mg}=0,2\left(mol\right)\)

\(\Rightarrow V_{H_2}=0,2.22,4=4,48\left(l\right)\)

b, \(n_{HCl}=2n_{H_2}=0,4\left(mol\right)\)

\(\Rightarrow C_{M_{HCl}}=\dfrac{0,4}{0,2}=2\left(M\right)\)

c, PT: \(HCl+KOH\rightarrow KCl+H_2O\)

Theo PT: \(n_{KOH}=n_{HCl}=0,4\left(mol\right)\)

\(\Rightarrow m_{ddKOH}=\dfrac{0,4.56}{5,6\%}=400\left(g\right)\)

\(\Rightarrow V_{ddKOH}=\dfrac{400}{1,045}\approx382,78\left(ml\right)\)

Ta có: \(n_{Mg}=\dfrac{9,6}{24}=0,4\left(mol\right)\)

PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)

Theo PT: \(n_{HCl}=2n_{Mg}=0,8\left(mol\right)\)

\(\Rightarrow C_{M_{HCl}}=\dfrac{0,8}{0,2}=4\left(M\right)\)

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

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

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

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

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

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

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

PT: \(Cu+2AgNO_3\rightarrow Cu\left(NO_3\right)_2+2Ag\)

a, m _{AgNO3 (pư)} = 250.17%.6% = 2,55 (g)

\(\Rightarrow n_{AgNO_3\left(pư\right)}=\dfrac{2,55}{170}=0,015\left(mol\right)\)

Theo PT: n_{Cu (pư)} = 1/2n_AgNO3 = 0,0075 (mol)

n_Ag = n_AgNO3 = 0,015 (mol)

⇒ m _{vật lấy ra} = 50 - m_{Cu (pư)} - m_Ag = 51,14 (g)

b, Ta có: m _{dd sau pư} = 0,0075.64 + 250 - 0,015.108 = 248,86 (g)

Theo PT: n_Cu(NO3)2 = 1/2n_AgNO3 = 0,0075 (mol)

\(\Rightarrow C\%_{Cu\left(NO_3\right)_2}=\dfrac{0,0075.188}{248,86}.100\%\approx0,57\%\)

\(C\%_{AgNO_3}=\dfrac{250.6\%-2,55}{248,86}.100\%\approx5\%\)

- Trích mẫu thử.

- Cho từng mẫu thử pư với dd NaOH.

+ Tan, xuất hiện bọt khí: Al

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

+ Không hiện tượng: Fe, Cu (1)

- Cho mẫu thử nhóm (1) pư với dd HCl.

+ Tan, có bọt khí: Fe

PT: \(Fe+2HCl\rightarrow FeCl_2+H_2\)

+ Không hiện tượng: Cu

- Dán nhãn.

Bài 3:

- Sử dụng Al để làm sạch Al₂(SO₄)₃ có lẫn FeSO₄.

PT: \(2Al+3FeSO_4\rightarrow Al_2\left(SO_4\right)_3+3Fe\)

Bài 5:

Ta có: \(n_{Al}=\dfrac{8,1}{27}=0,3\left(mol\right)\)

PT: \(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

a, \(n_{H_2}=\dfrac{3}{2}n_{Al}=0,45\left(mol\right)\Rightarrow V_{H_2}=0,45.24,79=11,1555\left(l\right)\)

b, \(n_{HCl}=3n_{Al}=0,9\left(mol\right)\)

\(\Rightarrow m_{ddHCl}=\dfrac{0,9.36,5}{12\%}=273,75\left(g\right)\)

c, \(n_{AlCl_3}=n_{Al}=0,3\left(mol\right)\)

\(\Rightarrow m_{AlCl_3}=0,3.133,5=40,05\left(g\right)\)

Bài 4:

- Chất có pư với Al trong điều kiện thích hợp: Cl₂, HCl, CuCl₂, ZnCl₂, S.

PT: \(2Al+3Cl_2\underrightarrow{t^o}2AlCl_3\)

\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

\(2Al+3CuCl_2\rightarrow2AlCl_3+3Cu\)

\(2Al+3ZnCl_2\rightarrow2AlCl_3+3Zn\)

\(2Al+3S\underrightarrow{t^o}Al_2S_3\)

- Chất có pư với Fe trong điều kiện thích hợp: Cl₂, HCl, CuCl₂, S.

PT: \(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)

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

\(Fe+CuCl_2\rightarrow FeCl_2+Cu\)

\(Fe+S\underrightarrow{t^o}FeS\)

a, X: Fe

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

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

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

b, X: Zn

PT: \(ZnO+H_2\underrightarrow{t^o}Zn+H_2O\)

\(Zn+H_2SO_4\rightarrow ZnSO_4+H_2\)

\(ZnSO_4+2NaOH\rightarrow Na_2SO_4+Zn\left(OH\right)_2\)

Ta có: \(m_{HCl}=200.7,3\%=14,6\left(g\right)\Rightarrow n_{HCl}=\dfrac{14,6}{36,5}=0,4\left(mol\right)\)

PT: \(K_2CO_3+2HCl\rightarrow2KCl+CO_2+H_2O\)

Theo PT: \(n_{CO_2}=n_{K_2CO_3}=\dfrac{1}{2}n_{HCl}=0,2\left(mol\right)\)

a, V_CO2 = 0,2.24,79 = 4,958 (l)

b, \(C_{M_{K_2CO_3}}=\dfrac{0,2}{0,15}=\dfrac{4}{3}\left(M\right)\)

Ta có: \(n_{Zn}=\dfrac{13}{65}=0,2\left(mol\right)\)

PT: \(Zn+2HCl\rightarrow ZnCl_2+H_2\)

a, n_H2 = n_Zn = 0,2 (mol)

⇒ V_H2 = 0,2.24,79 = 4,958 (l)

b, n_ZnCl2 = n_Zn = 0,2 (mol)

⇒ m_ZnCl2 = 0,2.136 = 27,2 (g)

c, \(H=\dfrac{3,225}{4,958}.100\%\approx65,05\%\)