\(Mg+H_2SO_4-->MgSO_4+H_2\)

x______x___________x______x

\(Zn+H_2SO_4-->ZnSO_4+H_2\)

y________y_______y_______y

\(n_{H_2}=\dfrac{17,92}{22,4}=0,8\left(mol\right)\)

Đặt x,y lần lượt là só mol của Mg và Zn

=>x+y=0,8(1)

mặt khác: 24x+65y=31,5 (2)

giải hệ (1),(2)

=>x=0,5 =>\(m_{Mg}=0,5.24=12\left(g\right)\)

y=0,3 => \(m_{Zn}=31,5-12=19,5\left(g\right)\)

\(m_{H_2SO_4}=0,8.98=78,4\left(g\right)\)

=>\(C\%_{H_2SO_4}=\dfrac{78,4}{300}.100=26,14\%\)

=>\(C_M=\dfrac{C\%.10.D}{M}=\dfrac{26,14.10.0,5}{98}=1,3\left(M\right)\)

Ta có: \(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

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

a, \(n_{Al}=\dfrac{2}{3}n_{H_2}=\dfrac{1}{6}\left(mol\right)\Rightarrow m_{Al}=\dfrac{1}{6}.27=4,5\left(g\right)\)

b, \(n_{H_2SO_4}=n_{H_2}=0,25\left(mol\right)\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,25}{0,2}=1,25\left(M\right)\)

c, \(n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{3}n_{H_2}=\dfrac{1}{12}\left(mol\right)\)

\(\Rightarrow m_{Al_2\left(SO_4\right)_3}=\dfrac{1}{12}.342=28,5\left(g\right)\)

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

b, Ta có: \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Theo PT: \(n_{Zn}=n_{H_2}=0,1\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Zn}=\dfrac{0,1.65}{10,5}.100\%\approx61,9\%\\\%m_{Cu}\approx38,1\%\end{matrix}\right.\)

c, \(n_{H_2SO_4}=n_{H_2}=0,1\left(mol\right)\)

\(\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,1}{0,5}=0,2\left(M\right)\)

\(n_{H_2}=\dfrac{2,24}{22,4}=0,1mol\\ a.Zn+H_2SO_4\rightarrow ZnSO_4+H_2\\ b.n_{Zn}=n_{H_2SO_4}=n_{H_2}=0,1mol\\ m_{Zn}=0,1.65=6,5g\\ \%m_{Zn}=\dfrac{6,5}{10,5}\cdot100\%=61,9\%\\ \%m_{Cu}=100\%-61,9=38,1\%\\ c.C_{M_{H_2SO_4}}=\dfrac{0,1}{0,5}=0,2M\)

Gọi x, y lần lượt là sô mol của Fe và Mg

Ta có: \(n_{H_2}=\dfrac{6,72}{22,4}=0,3\left(mol\right)\)

PTHH: 

Fe + H₂SO₄ ---> FeSO₄ + H₂ (1)

Mg + H₂SO₄ ---> MgSO₄ + H₂ (2)

a. Theo PT₍₁₎: \(n_{H_2}=n_{Fe}=x\left(mol\right)\)

Theo PT₍₂₎: \(n_{H_2}=n_{Mg}=y\left(mol\right)\)

\(\Rightarrow x+y=0,3\) (*)

Theo đề, ta có: 56x + 24y = 10.4 (**)

Từ (*) và (**), ta có HPT:

\(\left\{{}\begin{matrix}x+y=0,3\\56x+24y=10,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0,1\\y=0,2\end{matrix}\right.\)

\(\Rightarrow m_{Fe}=0,1.56=5,6\left(g\right);m_{Mg}=0,2.24=4,8\left(g\right)\)

b. Ta có: \(n_{hh}=0,1+0,2=0,3\left(mol\right)\)

Theo PT_(1,2): \(n_{H_2SO_4}=n_{hh}=0,3\left(mol\right)\)

Đổi 200ml = 0,2 lít

\(\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,3}{0,2}=1,5M\)

PTHH: 

\(Zn+H_2SO_4--->ZnSO_4+H_2\)

\(Cu+H_2SO_4--\times-->\)

a. Ta có: \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Theo PT: \(n_{Zn}=n_{H_2}=0,1\left(mol\right)\)

\(\Rightarrow m_{Zn}=0,1.65=6,5\left(g\right)\)

\(\Rightarrow\%_{m_{Zn}}=\dfrac{6,5}{19,3}.100\%=33,7\%\)

\(\%_{m_{Cu}}=100\%-33,7\%=66,3\%\)

b. Theo PT: \(n_{H_2SO_4}=n_{Zn}=0,1\left(mol\right)\)

Đổi 200ml = 0,2 lít

\(\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,1}{0,2}=0,5M\)

c. Ta có: \(V_{dd_{ZnSO_4}}=V_{dd_{H_2SO_4}}=0,2\left(lít\right)\)

Theo PT: \(n_{ZnSO_4}=n_{Zn}=0,1\left(mol\right)\)

\(\Rightarrow C_{M_{ZnSO_4}}=\dfrac{0,1}{0,2}=0,5M\)

\(Zn+H_2SO_4\rightarrow ZnSO_4+H_2\left(1\right)\)

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

Số mol khí H₂ thu được:

\(n_{H_2}=\dfrac{1,792}{22,4}=0,08mol\)

Gọi a và b lần lượt là số mol Zn và Al trong hỗn hợp.

Từ ( 1 ) và ( 2 ) ta có: 

\(\left\{{}\begin{matrix}a+\dfrac{3}{2}b=0,08\\65a+27b=3,79\end{matrix}\right.\rightarrow}\left\{{}\begin{matrix}a=0,05\\b=0,02\end{matrix}\right.\)

Khối lượng Zn: 65.0,05 = 3,25 g

Khối lượng Al: 27.0,02 = 0,54 gam

a, \(n_{H_2}=0,09\left(mol\right)\)

BT e, có: 2n_X = 2n_H2 ⇒ n_X = 0,09 (mol)

\(\Rightarrow\overline{M}_X=\dfrac{2,64}{0,09}=29,33\left(g/mol\right)\)

Mà: A, B thuộc 2 chu kì liên tiếp.

→ Mg và Ca.

Ta có: \(\left\{{}\begin{matrix}24n_{Mg}+40n_{Ca}=2,64\\2n_{Mg}+2n_{Ca}=0,09.2\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,06\left(mol\right)\\n_{Ca}=0,03\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,06.24}{2,64}.100\%\approx54,55\%\\\%m_{Ca}\approx45,45\%\end{matrix}\right.\)

b, BTNT H, có: \(n_{H_2SO_4}=n_{H_2}=0,09\left(mol\right)\Rightarrow V_{ddH_2SO_4}=\dfrac{0,09}{2}=0,045\left(l\right)\)

BTNT Mg: n_MgSO4 = n_Mg = 0,06 (mol)

\(\Rightarrow C_{M_{MgSO_4}}=\dfrac{0,06}{0,045}=\dfrac{4}{3}\left(M\right)\)

a, Ta có: 27n_Al + 56n_Fe = 27,8 (1)

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

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

Theo PT: \(n_{H_2}=\dfrac{3}{2}n_{Al}+n_{Fe}=\dfrac{17,353}{24,79}=0,7\left(mol\right)\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Al}=0,2\left(mol\right)\\n_{Fe}=0,4\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,2.27}{27,8}.100\%\approx19,42\%\\\%m_{Fe}\approx80,58\%\end{matrix}\right.\)

b, \(n_{H_2SO_4}=n_{H_2}=0,7\left(mol\right)\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,7}{0,5}=1,4\left(M\right)\)

a.\(n_{H_2}=\dfrac{7,28}{22,4}=0,325mol\)

Gọi \(\left\{{}\begin{matrix}n_{Al}=x\\n_{Zn}=y\end{matrix}\right.\) \(\left(mol\right)\)  \(\rightarrow27x+65y=10,55\left(g\right)\) (1)

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

 x                                 1/2 x          3/2 x       ( mol )

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

 y                            y               y     ( mol )

\(\rightarrow\dfrac{3}{2}x+y=0,325\left(mol\right)\) (2)

\(\left(1\right);\left(2\right)\rightarrow\left\{{}\begin{matrix}x=0,15\\y=0,1\end{matrix}\right.\)

\(\rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,15.27}{10,55}.100\%=38,38\%\\\%m_{Zn}=100\%-38,38\%=61,62\%\end{matrix}\right.\)

b.\(\left\{{}\begin{matrix}n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}.0,15=0,075\\n_{ZnSO_4}=0,1\end{matrix}\right.\) ( mol )

\(\left\{{}\begin{matrix}C_{M_{Al_2\left(SO_4\right)_3}}=\dfrac{0,075}{0,8}=0,09M\\C_{M_{ZnSO_4}}=\dfrac{0,1}{0,8}=0,125M\end{matrix}\right.\)