\(a) Mg + H_2SO_4 \to MgSO_4 + H_2\\ 2Al + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2\\ b) n_{Mg} = a(mol) ; n_{Al} = b(mol) \Rightarrow 24a + 27b = 7,5(1)\\ n_{H_2} = a + 1,5b = \dfrac{7,84}{22,4} = 0,35(2)\\ (1)(2) \Rightarrow a = 0,2 ; b = 0,1\\ \%m_{Mg} = \dfrac{0,2.24}{7,5}.100\% = 64\%\\ \%m_{Al} = 100\% - 64\% = 36\%\)

Giả sử: \(\left\{{}\begin{matrix}n_{Al}=x\left(mol\right)\\n_{Al_2O_3}=y\left(mol\right)\end{matrix}\right.\)

⇒ 27x + 102y = 18,54 (1)

Ta có: \(n_{H_2}=\dfrac{4,032}{22,4}=0,18\left(mol\right)\)

Theo ĐLBT mol e, có: 3x = 0,18.2 (2)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,12\left(mol\right)\\y=0,15\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,12.27}{18,54}.100\%\approx17,5\%\\\%m_{Al_2O_3}\approx82,5\%\end{matrix}\right.\)

_ Khi cho hỗn hợp tác dụng với H₂SO₄ đặc, nóng.

Giả sử: \(n_{SO_2}=a\left(mol\right)\)

Theo ĐLBT mol e, có: 3.0,12 = 2a ⇒ x = 0,18 (mol)

Ta có: \(n_{KOH}=0,36.1=0,36\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{n_{KOH}}{n_{SO_2}}=\dfrac{0,36}{0,18}=2\)

⇒ Pư tạo muối trung hòa K₂SO₃.

PT: \(SO_2+2KOH\rightarrow K_2SO_3+H_2O\)

___0,18____________0,18 (mol)

\(\Rightarrow C_{M_{K_2SO_3}}=\dfrac{0,18}{0,36}=0,5M\)

Bạn tham khảo nhé!

\(n_{H_2}=\dfrac{4,48}{22,4}=0,2mol\\ Zn+H_2SO_4\rightarrow ZnSO_4+H_2\\ FeO+H_2SO_4\rightarrow FeSO_4+H_2O\\ n_{Zn}=n_{H_2}=0,2mol\\ \%m_{Zn}=\dfrac{0,2.65}{20}\cdot100\%=65\%\\ \%m_{Fe}=100\%-65\%=35\%\)

Bài 2 : 

a)

$Mg + 2HCl \to MgCl_2 + H_2$
$2Al + 6HCl \to 2AlCl_3 + 3H_2$
$n_{H_2} = \dfrac{5,6}{22,4} = 0,25(mol)$
$n_{HCl} = 2n_{H_2} = 0,5(mol)$
$m_{HCl} = 0,5.36,5 = 18,25(gam)$

b)

Bảo toàn khối lượng : 

$m_A = 22,85 + 0,25.2 - 18,25 = 5,1(gam)$

\(n_{H_2}=\dfrac{4.48}{22.4}=0.2\left(mol\right)\)

\(Zn+2HCl\rightarrow ZnCl_2+H_2\)

\(0.2.........0.4.........0.2......0.2\)

\(m_{Zn}=0.2\cdot65=13\left(g\right)\Rightarrow m_{ZnO}=14.6-13=1.6\left(g\right)\)

\(\%Zn=\dfrac{13}{14.6}\cdot100\%=89.04\%\)

\(\%ZnO=100\%-89.04\%=10.96\%\)

\(n_{ZnO}=\dfrac{1.6}{81}\approx0.02\left(mol\right)\)

\(ZnO+2HCl\rightarrow ZnCl_2+H_2O\)

\(0.02........0.04........0.02........0.02\)

\(n_{HCl}=0.4+0.04=0.44\left(mol\right)\)

\(C_{M_{HCl}}=\dfrac{0.44}{0.8}=0.55\left(M\right)\)

Eeeee ngồi tính sang chấn thật nó ra số xấu lần mò hơn 20p chưa biết tính sai chỗ nào

\(n_{H_2}=n_{H_2SO_4}=\dfrac{11.2}{22.4}=0.5\left(mol\right)\)

\(BTKL:\)

\(m_{Muối}=17.5+0.5\cdot98-0.5\cdot2=65.5\left(g\right)\)

VddH2SO4=0,50,5=1M

\(n_{H_2SO_4}=n_{H_2}=a(mol)\\ BTKL:\\ m_{hh}+m_{H_2SO_4}=m_Y+m_{H_2}\\ 2,49+98.a= 8,25+2.a\\ \to a=0,06(mol)\\ a/ m_{H_2SO_4}=0,06.98=5,88(g)\\ b/ V_{H_2}=0,06.22,4=1,334(l)\)