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\(n_{H_2}=\dfrac{7,84}{22,4}=0,35mol\)
Gọi \(\left\{{}\begin{matrix}n_{Fe}=x\\n_{Zn}=y\end{matrix}\right.\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
x x ( mol )
\(Zn+2HCl\rightarrow ZnCl_2+H_2\)
y y ( mol )
Ta có:
\(\left\{{}\begin{matrix}56x+65y=21,4\\x+y=0,35\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=0,15\\y=0,2\end{matrix}\right.\)
\(\Rightarrow m_{Fe}=0,15.56=8,4g\)
\(\Rightarrow m_{Zn}=0,2.65=13g\)
\(\%m_{Fe}=\dfrac{8,4}{21,4}.100=39,25\%\)
\(\%m_{Zn}=100\%-39,25\%=60,75\%\)
\(m_{FeCl_2}=0,15.127=19,05g\)
\(m_{ZnCl_2}=0,2.136=27,2g\)
\(Đặt:n_{MnO_2}=a\left(mol\right),n_{KMnO_4}=b\left(mol\right)\)
\(m_{hh}=87a+158b=37.96\left(g\right)\left(1\right)\)
\(n_{Cl_2}=\dfrac{10.08}{22.4}=0.45\left(mol\right)\)
\(2KMnO_4+16HCl\rightarrow2KCl+2MnCl_2+5Cl_2+8H_2O\)
\(MnO_2+4HCl\rightarrow MnCl_2+Cl_2+2H_2O\)
\(n_{Cl_2}=a+2.5b=0.45\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.4,b=0.02\)
\(\%MnO_2=\dfrac{0.4\cdot87}{37.96}\cdot100\%=91.68\%\\\%KMnO_4=100-91.68=8.32\% \)
\(m_M=m_{KCl}+m_{MnCl_2}=0.02\cdot74.5+\left(0.4+0.02\right)\cdot126=54.41g\)
m(Zn,Mg)=25-6,5= 18,5(g)
nHCl(p.ứ)= 0,8.2 : 125%= 1,28(mol)
PTHH: Zn + 2 HCl -> ZnCl2 + H2
x__________2x_____x____x(mol)
Mg + 2 HCl -> MgCl2 + H2
y______2y____y_____y(mol)
Ta có hpt:
\(\left\{{}\begin{matrix}65x+24y=18,5\\2x+2y=1,28\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{157}{2050}\\y=\dfrac{231}{410}\end{matrix}\right.\)
=>
\(\%mAg=\dfrac{6,5}{25}.100=26\%\\ \%mZn=\dfrac{\dfrac{157}{2050}.65}{25}.100\approx19,912\%\\ \rightarrow\%mMg\approx54,088\%\)
a) PTHH: \(Fe+2HCl\rightarrow FeCl_2+H_2\uparrow\) (1)
\(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\) (2)
b) Dựa vào đề, ta thấy chắc chắn HCl dư
Ta có: \(\Sigma n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)
Gọi số mol của Fe là \(a\) \(\Rightarrow n_{H_2\left(1\right)}=a\)
Gọi số mol của Mg là \(b\) \(\Rightarrow n_{H_2\left(2\right)}=b\)
Ta lập được hệ phương trình:
\(\left\{{}\begin{matrix}56a+24b=8\\a+b=0,2\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{Fe}=56\cdot0,1=5,6\left(g\right)\\m_{Mg}=24\cdot0,1=2,4\left(g\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{5,6}{8}\cdot100\%=70\%\\\%m_{Mg}=30\%\end{matrix}\right.\)
c) Theo các PTHH: \(n_{FeCl_2}=n_{MgCl_2}=n_{Fe}=n_{Mg}=0,1mol\)
\(\Rightarrow\left\{{}\begin{matrix}m_{FeCl_2}=0,1\cdot127=12,7\left(g\right)\\m_{MgCl_2}=0,1\cdot95=9,5\left(g\right)\end{matrix}\right.\) \(\Rightarrow m_{muối}=22,2\left(g\right)\)
d) Ta có: \(\Sigma n_{HCl}=\dfrac{500\cdot16\%}{36,5}=\dfrac{160}{73}\left(mol\right)\)
\(\Rightarrow n_{HCl\left(dư\right)}=\dfrac{654}{365}\left(mol\right)\) \(\Rightarrow m_{HCl\left(dư\right)}=\dfrac{654}{365}\cdot36,5=65,4\left(g\right)\)
Mặt khác: \(m_{dd}=m_{hh}+m_{ddHCl}-m_{H_2}=507,6\left(g\right)\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{FeCl_2}=\dfrac{12,7}{507,6}\cdot100\%\approx2,5\%\\C\%_{MgCl_2}=\dfrac{9,5}{507,6}\cdot100\%\approx1,87\%\\C\%_{HCl\left(dư\right)}=\dfrac{65,4}{507,6}\cdot100\%\approx12,88\%\end{matrix}\right.\)
a) nCl2=7,28/22,4=0,325(mol)
=> mCl2=0,325.71=23,075(mol)
=> m(muối)= m(hh)+ mCl2= 10,45+23,075=33,525(g)
b) PTHH: 2 Al + 3 Cl2 -to-> 2 AlCl3
a__________1,5a(mol)
Cu + Cl2 -to-> CuCl2
b___b(mol)
Ta có hpt:
\(\left\{{}\begin{matrix}27a+64b=10,45\\1,5a+b=0,325\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,15\\b=0,1\end{matrix}\right.\)
=> mCu=0,1.64=6,4(g)
=>%mCu= (6,4/10,45).100=61,244%
=>%mAl=38,756%
Đặt :
nFe = x mol
nMgO = y mol
mX = 56x + 40y = 13.6 (g) (1)
Fe + 2HCl => FeCl2 + H2
x____________x
MgO + 2HCl => MgCl2 + H2O
y______________y
mM = mFeCl2 + mMgCl2 = 127x + 95y = 31.7 (2)
(1) , (2) :
x = 0.1
y = 0.2
%Fe = 5.6/13.6 * 100% = 41.17%
%MgO = 58.82%
nKOH = 0.1 * 0.2 = 0.02 (mol)
KOH + HCl => KCl + H2O
0.02____0.02
nHCl (pư) = 2nFe + 2nMgO = 0.1*2 + 0.2*2 = 0.6 (mol)
nHCl = 0.02 + 0.6 = 0.62 (mol)
VddHCl = 0.62/0.5 = 1.24 (M)
Gọi \(\left\{{}\begin{matrix}n_{CuO}=x\\n_{MgO}=y\end{matrix}\right.\)
\(CuO+2HCl\rightarrow CuCl_2+H_2O\)
x x ( mol )
\(MgO+2HCl\rightarrow MgCl_2+H_2O\)
y y ( mol )
Ta có:
\(\left\{{}\begin{matrix}80x+40y=16\\135x+95y=32,5\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=0,1\\y=0,2\end{matrix}\right.\)
\(\Rightarrow m_{CuO}=0,1.80=8g\)
\(\Rightarrow m_{MgO}=0,2.40=8g\)
\(\%m_{CuO}=\dfrac{8}{16}.100=50\%\)
\(\%m_{MgO}=\dfrac{8}{16}.100=50\%\)
\(m_{CuCl_2}=0,1.135=13,5g\)
\(m_{MgCl_2}=0,2.95=19g\)