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Câu 1:
Đặt \(n_{Al}=x(mol);n_{Fe}=y(mol)\Rightarrow 27x+56y=0,83(1)\)
\(n_{H_2}=\dfrac{0,56}{22,4}=0,025(mol)\\ 2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2\\ Fe+H_2SO_4\to FeSO_4+H_2\\ \Rightarrow 1,5x+y=0,025(2)\\ (1)(2)\Rightarrow x=y=0,01(mol)\\ \Rightarrow \%_{Al}=\dfrac{0,01.27}{0,83}.100\%=32,53\%\\ \Rightarrow \%_{Fe}=100\%-32,53\%=67,47\%\)
Câu 2:
Đặt \(n_{Al}=x(mol);n_{Mg}=y(mol)\Rightarrow 27x+24y=4,5(1)\)
\(n_{H_2}=\dfrac{5,04}{22,4}=0,225(mol)\\ 2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2\\ Mg+H_2SO_4\to MgSO_4+H_2\\ \Rightarrow 1,5x+y=0,225(2)\\ (1)(2)\Rightarrow x=0,1(mol);y=0,075(mol)\\ \Rightarrow \%_{Al}=\dfrac{0,1.27}{4,5}.100\%=60\%\\ \Rightarrow \%_{Mg}=100\%-60\%=40\%\)
Dạng PP hai dòng:
\(PTHH:2A+Cl_2\to 2ACl\\ \Rightarrow n_A=n_{ACl}\\ \Rightarrow \dfrac{9,2}{M_A}=\dfrac{23,4}{M_A+35,5}\\ \Rightarrow M_A=23(g/mol)\)
Vậy A là natri
PTHH: \(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)
a_______a_______a_____a (mol)
\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\uparrow\)
2b______3b__________b_____3b (mol)
Ta lập HPT: \(\left\{{}\begin{matrix}56a+27\cdot2b=11\\a+3b=0,2\cdot2=0,4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{0,1\cdot56}{11}\cdot100\%\approx50,91\%\\\%m_{Al}=49,09\%\end{matrix}\right.\)
Theo các PTHH: \(\left\{{}\begin{matrix}n_{H_2}=0,4\left(mol\right)\\n_{FeSO_4}=0,1\left(mol\right)\\n_{Al_2\left(SO_4\right)_3}=0,3\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}V_{H_2}=0,4\cdot22,4=8,96\left(l\right)\\C_{M_{FeSO_4}}=\dfrac{0,1}{0,2}=0,5\left(M\right)\\C_{M_{Al_2\left(SO_4\right)_3}}=\dfrac{0,3}{0,2}=1,5\left(M\right)\end{matrix}\right.\)
a) nH2SO4=0,4(mol)
Đặt: nFe=x(mol); nAl=y(mol) (x,y>0)
PTHH: Fe + H2SO4 -> FeSO4 + H2
x________x______x______x(mol)
2Al + 3 H2SO4 -> Al2(SO4)3 + 3 H2
y____1,5y_______0,5y_______1,5y(mol)
Ta có hpt:
\(\left\{{}\begin{matrix}56x+27y=11\\x+1,5y=0,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0,1\\y=0,2\end{matrix}\right.\)
=> mFe=0,1.56=5,6(g)
=>%mFe=(5,6/11).100=50,909%
=>%mAl= 49,091%
b) V(H2,đktc)=0,4.22,4=8,96(l)
c) nAl2(SO4)3= 0,5y=0,5.0,2=0,1(mol)
nFeSO4=x=0,1(mol)
Vddsau=VddH2SO4=0,2(l)
=>CMddAl2(SO4)3= 0,1/0,2=0,5(M)
CMddFeSO4=0,1/0,2=0,5(M)
\(n_{Al}=a\left(mol\right)\)
\(n_{Fe}=b\left(mol\right)\)
\(m=27a+56b=19.3\left(g\right)\left(1\right)\)
\(n_{H^+}=0.2\cdot2+0.2\cdot2.25\cdot2=1.3\left(mol\right)\)
\(2Al+6H^+\rightarrow2Al^{3+}+3H_2\)
\(Fe+2H^+\rightarrow Fe^{2+}+H_2\)
\(n_{H^+}=3a+2b=1.3\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.3,b=0.2\)
\(\%Al=\dfrac{0.3\cdot27}{19.3}\cdot100\%=41.96\%\)
\(\%Fe=58.04\%\)
\(b.\)
\(n_{H_2}=\dfrac{1}{2}n_{H^+}=0.65\left(mol\right)\)
Bảo toàn khối lượng :
\(m_{Muối}=19.3+0.4\cdot36.5+0.45\cdot98-0.65\cdot2=76.7\left(g\right)\)
a)
$2Al + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2$
$Fe + H_2SO_4 \to FeSO_4 + H_2$
b)
Gọi $n_{Al} = a(mol) ; n_{Fe} = b(mol) \Rightarrow 27a + 56b = 0,83(1)$
Theo PTHH : $n_{H_2} = 1,5a + b = \dfrac{0,56}{22,4} = 0,025(2)$
Từ (1)(2) suy ra : a = 0,01; b = 0,01
$\%m_{Al} = \dfrac{0,01.27}{0,84}.100\% = 32,1\%$
$\%m_{Fe} = 100\% - 32,1\% = 67,9\%$
a) PTHH: 2Al + 3H2SO4 --> Al2(SO4)3 + 3H2
b) \(n_{H_2}=\dfrac{0,672}{22,4}=0,03\left(mol\right)\)
PTHH: 2Al + 3H2SO4 --> Al2(SO4)3 + 3H2
_____0,02<---0,03<---------------------0,03
=> \(\left\{{}\begin{matrix}\%Al=\dfrac{0,02.27}{2,16}.100\%=25\%\\\%Cu=100\%-25\%=75\%\end{matrix}\right.\)
c) mH2SO4 = 0,03.98 = 2,94 (g)
=> \(C\%\left(H_2SO_4\right)=\dfrac{2,94}{200}.100\%=1,47\%\)
\(n_{H_2SO_4}=0,2.2=0,4\left(mol\right)\)
Fe + H2SO4 → FeSO4 + H2
2Al + 3H2SO4 → Al2(SO4)3 + 3H2
Gọi x,y lần lượt là số mol Fe, Al
\(\left\{{}\begin{matrix}56x+27y=11\\x+\dfrac{3}{2}y=0,4\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=0,1\\y=0,2\end{matrix}\right.\)
=>\(\%m_{Fe}=\dfrac{0,1.56}{11}.100=50,91\%\)
=> %m Al = 100 - 50,91 =49,09 %
b)Theo PT: \(n_{H_2}=n_{H_2SO_4}=0,4\left(mol\right)\)
=> \(V_{H_2}=0,4.22,4=8,96\left(l\right)\)
c) \(CM_{FeSO_4}=\dfrac{0,1}{0,2}=0,5M\)
\(CM_{Al_2\left(SO_4\right)_3}=\dfrac{\dfrac{0,2}{2}}{0,2}=0,5M\)
\(n_{H_2}=\dfrac{0,56}{22,4}=0,025(mol)\\ n_{Fe}=x(mol);n_{Al}=y(mol)\\ \Rightarrow 56x+27y=0,83(1)\\ Fe+H_2SO_4\to FeSO_4+H_2\\ 2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2\\ \Rightarrow x+1,5y=0,025(2)\\ (1)(2)\Rightarrow \begin{cases} x=0,01(mol)\\ y=0,01(mol) \end{cases}\Rightarrow \begin{cases} \%_{Fe}=\dfrac{0,01.56}{0,83}.100\%=67,47\%\\ \%_{Al}=100\%-67,47\%=32,53\% \end{cases}\)
a) Gọi `n_{Al} = a (mol); n_{Fe} = b (mol)`
PTHH:
`2Al + 3H_2SO_4 -> Al_2(SO_4)_3 + 3H_2`
`Fe + H_2SO_4 -> FeSO_4 + H_`
b) `n_{H_2} = (0,56)/(22,4) = 0,025 (mol)`
Theo PT: `n_{H_2} = n_{Fe} + 3/2 n_{Al}`
`=> b + 1,5a = 0,025`
Giải hpt \(\left\{{}\begin{matrix}27a+56b=0,83\\1,5a+b=0,025\end{matrix}\right.\Leftrightarrow a=b=0,01\)
=> \(\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,01.27}{0,83}.100\%=32,53\%\\\%m_{Fe}=100\%-32,53\%=67,47\%\end{matrix}\right.\)
PTHH:
Zn + H2SO4 ---> ZnSO4 + H2 (1)
2Al + 3H2SO4 ---> Al2(SO4)3 + 3H2 (2)
Ta có: \(n_{H_2}=\dfrac{1,792}{22,4}=0,08\left(mol\right)\)
Gọi x, y lần lượt là số mol của Zn và Al
a. Theo PT(1): \(n_{H_2}=n_{Zn}=x\left(mol\right)\)
Theo PT(2): \(n_{H_2}=\dfrac{3}{2}.n_{Al}=\dfrac{3}{2}y\left(mol\right)\)
=> \(x+\dfrac{3}{2}y=0,8\) (*)
Theo đề, ta có: 65x + 27y = 3,79 (**)
Từ (*) và (**), ta có HPT:
\(\left\{{}\begin{matrix}x+\dfrac{3}{2}y=0,8\\65x+27y=3,79\end{matrix}\right.\)
(Ra số âm, bn xem lại đề nhé.)
a, Ta có: 27nAl + 56nFe = 0,83 (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: \(n_{H_2}=\dfrac{3}{2}n_{Al}+n_{Fe}=\dfrac{0,56}{22,4}=0,025\left(mol\right)\left(2\right)\)
Từ (1) và (2) \(\Rightarrow n_{Al}=n_{Fe}=0,01\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,01.27}{0,83}.100\%\approx32,53\%\\\%m_{Fe}\approx67,47\%\end{matrix}\right.\)
b, nH2SO4 = nH2 = 0,025 (mol)
\(\Rightarrow m_{ddH_2SO_4}=\dfrac{0,025.98}{20\%}=12,25\left(g\right)\)