n_H2=0.56:22,4=0,025 mol 
Fe+H₂SO₄----->FeSO₄+H₂ 
2AL+3H2SO4----->AL2(SO4)3 +3H2 
Gọi x,y làn lượt là số mol Fe và AL 
ta có hệ pt 
$\{\begin{array}{c}56x+27y=0,83\\ x+1,5y=0,025\end{array}$
$\{\begin{array}{c}x=0,01mol\\ y=0,01mol\end{array}$
m_Fe=0,01.56=0,56 g 
m_Al=0,83-0,56=0,27 g 
%mFe=(0,56:0,83).100=67,47% 
%m_Al=100-67,47=32,53%

\(n_{H_2}=\dfrac{5,6}{22,4}=0,25(mol)\\ a,PTHH:Fe+2HCl\to FeCl_2+H_2\\ 2Al+6HCl\to 2AlCl_3+3H_2\)

\(b,\) Đặt \(n_{Fe}=x(mol);n_{Al}=y(mol)\)

\(\Rightarrow 56x+27y=8,3(1)\)

Theo PTHH: \(x+1,5y=0,25(2)\)

\((1)(2)\Rightarrow x=y=0,1(mol)\\ \Rightarrow \%_{Fe}=\dfrac{0,1.56}{8,3}.100\%=67,47\%\\ \%_{Al}=100\%-67,47\%=32,53\%\)

\(a,n_{H_2}=\dfrac{1,68}{22,4}=0,075\left(mol\right)\)

PTHH: \(Mg+H_2SO_4\rightarrow MgSO_4+H_2\uparrow\)

           0,075<-------------------------0,075

Cu không phản ứng với H₂SO₄ loãng

b, \(m_{Mg}=0,075.24=1,8\left(g\right)\)

\(\rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{1,8}{8}.100\%=22,5\%\\\%m_{Cu}=100\%-22,5\%=77,5\%\end{matrix}\right.\)

\(n_{H_2}=\dfrac{1,68}{22,4}=0,075\left(mol\right)\\ pthh:Mg+H_2SO_4\rightarrow MgSO_4+H_2\) 
            0,075                                0,075 
         \(Cu+H_2SO_4-x->\) 
          \(m_{Mg}=0,075.24=1,6\left(g\right)\\ m_{Cu}=8-1,6=6,4\left(g\right)\) 
\(\%m_{Cu}=\dfrac{6,4}{8}.100\%=80\%\\ \%m_{Mg}=100-80\%=20\%\)

n_H2 \(\approx\)0,2 (mol)

Mg + 2HCl \(\rightarrow\) MgCl₂ + H₂ (1)

0,2 <------------ 0,2 <----- 0,2 (mol)

MgO + 2HCl \(\rightarrow\) MgCl₂ + H₂O (2)

b) %^mMg = \(\frac{0,2.24}{8,8}\) . 100% =54,55%

%^mMgO = 45,45%

c) m_MgO = 8,8 - 0,2 . 24 = 4(g)

=> n_MgO=0,1 (mol)

Theo pt(2) n_MgCl2 = n_Mg = 0,1 (mol)

=> \(\Sigma n_{MgCl_2}\) = 0,2 + 0,1 = 0,3 (mol)

m_muối = 0,3 . 95 = 28,5 (g)

a, \(Fe+2HCl\rightarrow FeCl_2+H_2\)

b, \(n_{H_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)\)

Theo PT: \(n_{Fe}=n_{H_2}=0,4\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{0,4.56}{35}.100\%=64\%\\\%m_{Cu}=36\%\end{matrix}\right.\)

giúp mình với =((

a) 

$Cu + 2H_2SO_4 \to CuSO_4 + SO_2 + H_2O$
$2Fe  + 6H_2SO_4 \to Fe_2(SO_4)_3 + 3SO_2 + 6H_2O$

b) n Cu =a (mol) ; n Fe = b(mol)

=> 64a + 56b = 12(1)

n SO2 = a + 1,5b = 5,6/22,4 = 0,25(2)

(1)(2) suy ra a = b = 0,1

%m Cu = 0,1.64/12  .100% = 53,33%
%m Fe = 100% -53,33% = 46,67%

c)

n CuSO4 = a = 0,1(mol)

n Fe2(SO4)3 = 0,5a = 0,05(mol)

m muối = 0,1.160  + 0,05.400 = 36(gam)

d) n H2SO4 = 2n SO2 = 0,5(mol)

V H2SO4 = 0,5/2 = 0,25(lít)