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Đặt nAl=a(mol); nFe=b(mol) (a,b>0)
Ta có: nH2=8,96/22,4=0,4(mol)
PTHH: 2 Al + 6 HCl -> 2 AlCl3 + 3 H2
a_________3a____a____1,5a(mol)
Fe +2 HCl -> FeCl2 + H2
b__2b____b____b(mol)
Ta có hpt:
\(\left\{{}\begin{matrix}27a+56b=16,7\\1,5a+b=0,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,25\end{matrix}\right.\)
=> mAl= 0,1.27=2,7(g) =>%mAl= (2,7/16,7).100=16,17%
=> CHỌN B
Đặt x,y, z lần lượt là số mol của Na,Al,Mg trong m gam hỗn hợp A
m gam A + H2O dư
\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)
x--------------------x--------->0,5x
2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2
x<------x-------------------------------------->1,5x
=> \(0,5x+1,5x=\dfrac{2,24}{22,4}=0,1\left(mol\right)\) (1)
2m gam A + NaOH
\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)
2x------------------------------->x
2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2
2y---------------------------------------------->3y
=> \(x+3y=\dfrac{8,96}{22,4}=0,4\left(mol\right)\) (2)
3m gam A + HCl
\(Na+HCl\rightarrow NaCl+\dfrac{1}{2}H_2\)
3x--------------------------->1,5x
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
3y----------------------------->4,5y
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
3z----------------------------->3z
=> \(1,5x+4,5y+3z=\dfrac{22,4}{22,4}=1\left(mol\right)\) (3)
Từ (1), (2), (3) =>\(\left\{{}\begin{matrix}x=0,05\\y=\dfrac{7}{60}\\z=\dfrac{2}{15}\end{matrix}\right.\)
=> \(m_{Na}=0,05.23=1,15\left(g\right)\)
\(m_{Al}=\dfrac{7}{60}.27=3,15\left(g\right)\)
\(m_{Mg}=\dfrac{2}{15}.24=3,2\left(g\right)\)
=> \(m=1,15+3,15+3,2=7,5\left(g\right)\)
=> \(\%m_{Na}=\dfrac{1,15}{7,5}.100=15,33\%\)
\(\%m_{Al}=\dfrac{3,15}{7,5}.100=42\%\)
\(\%m_{Mg}=\dfrac{3,2}{7,5}.100=42,67\%\)
\(2Na+2H2O\rightarrow2NaOH+H2\left(1\right)\)
\(2Al+2NaOH+2H2O\rightarrow2NaAlO2+3H2\left(2\right)\)
\(2Al+6HCl\rightarrow2AlCl3+3H2\left(3\right)\)
\(2Na+2HCl\rightarrow2NaCl+H2\left(4\right)\)
\(Mg+2HCl\rightarrow MgCl2+H2\left(5\right)\)
\(n_{H2\left(1\right)}=0,1\left(mol\right)\rightarrow n_{Na}=0,2\left(mol\right)\rightarrow m_{Na}=4,6\left(g\right)\)
\(n_{H2\left(2\right)}=0,4\left(mol\right)\Rightarrow n_{Al}=\dfrac{4}{15}\left(mol\right)\Rightarrow m_{Al}=7,2\left(g\right)\)
\(\Rightarrow n_{H2\left(3\right)}=\dfrac{3}{2}n_{Al}=0,4\left(mol\right)\)
\(n_{H2\left(4\right)}=\dfrac{1}{2}n_{Na}=0,1\left(mol\right)\)
\(\Rightarrow n_{H2\left(5\right)}=1-0,4-0,1=0,5\left(mol\right)\)
\(\Rightarrow n_{Mg}=0,5\left(mol\right)\Rightarrow m_{Mg}=12\left(g\right)\)
\(\Rightarrow m=12+4,6+7,2=23,8\left(g\right)\)
\(\%m_{Na}=\dfrac{4,6}{23,8}.100\%=19,33\%\)
\(\%m_{Al}=\dfrac{7,2}{23,8}.100\%=30,25\%\)
\(\%m_{Mg}=100-19,33-30,25=50,42\%\)
Chúc bạn học tốt
\(a)n_{H_2}=\dfrac{3,36}{22,4}=0,15mol\\ 2Al+6HCl\rightarrow2AlCl_3+3H_2\)
0,1 0,3 0,1 0,15
\(\%m_{Al}=\dfrac{0,1.27}{10,7}\cdot100\%=25,23\%\\ \%m_{MgO}=100\%-25,23\%=76,75\%\\ b)n_{MgO}=\dfrac{10,7-0,1.27}{40}=0,2mol\\ MgO+2HCl\rightarrow MgCl_2+H_2O\)
0,2 0,4
\(V_{ddHCl}=\dfrac{0,4+0,3}{0,5}=1,4l\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\\ 0,2mol\text{:}0,4mol\rightarrow0,2mol\text{:}0,2mol\)
\(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)
\(n_{HCl}=0,5.1=0,5\left(mol\right)\)
Ta có \(0,2< \dfrac{0,5}{2}\) nên HCl dư.
\(n_{HCldu}=0,5-0,4=0,1\left(mol\right)\)
\(m_{HCldu}=0,1.36,5=3,65\left(g\right)\)
a) \(n_{Al}=\dfrac{0,54}{27}=0,02\left(mol\right)\)
PTHH: 2Al + 6HCl --> 2AlCl3 + 3H2
_____0,02->0,06---->0,02--->0,03
=> VH2 = 0,03.22,4 = 0,672 (l)
b) mHCl = 0,06.36,5 = 2,19 (g)
=> \(C\%_{ddHCl}=\dfrac{2,19}{100}.100\%=2,19\%\)
`a)`
`2Al+6HCl->2AlCl_3+3H_2`
`n_{Al}={0,54}/{27}=0,02(mol)`
`n_{H_2}=3/{2}n_{Al}=0,03(mol)`
`V_{H_2}=0,03.22,4=0,672(l)`
`b)`
`n_{HCl}=2n_{H_2}=0,06(mol)`
`C%_{HCl}={0,06.36,5}/{100}.100%=2,19%`
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)
\(n_{H_2SO_4}=0,2.2=0,4\left(mol\right)\)
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) \(CM_{FeSO_4}=\dfrac{0,1}{0,2}=0,5M\)
\(CM_{Al_2\left(SO_4\right)_3}=\dfrac{\dfrac{0,2}{2}}{0,2}=0,5M\)
\(n_{Al}=a\left(mol\right)\)
\(n_{Fe}=b\left(mol\right)\)
\(m=27a+56b=19.3\left(g\right)\left(1\right)\)
\(n_{H^+}=0.2\cdot2+0.2\cdot2.25\cdot2=1.3\left(mol\right)\)
\(2Al+6H^+\rightarrow2Al^{3+}+3H_2\)
\(Fe+2H^+\rightarrow Fe^{2+}+H_2\)
\(n_{H^+}=3a+2b=1.3\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.3,b=0.2\)
\(\%Al=\dfrac{0.3\cdot27}{19.3}\cdot100\%=41.96\%\)
\(\%Fe=58.04\%\)
\(b.\)
\(n_{H_2}=\dfrac{1}{2}n_{H^+}=0.65\left(mol\right)\)
Bảo toàn khối lượng :
\(m_{Muối}=19.3+0.4\cdot36.5+0.45\cdot98-0.65\cdot2=76.7\left(g\right)\)