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Nhận thấy : n HCl = 2 n H 2 = 2 x 3,136/22,4 = 0,28 mol
Theo định luật bảo toàn khối lượng có :
Khối lượng muối = 5,1 + 0,28.36,5 - 0,14.2 = 15,04 (gam)
a.\(n_{H_2}=\dfrac{V_{H_2}}{22,4}=\dfrac{8,96}{22,4}=0,4mol\)
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:
\(\left\{{}\begin{matrix}56x+65y=25,55\\x+y=0,4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=0,05\\y=0,35\end{matrix}\right.\)
\(\Rightarrow m_{Fe}=0,05.56=2,8g\)
\(\Rightarrow m_{Zn}=0,35.65=22,75g\)
\(\%m_{Fe}=\dfrac{2,8}{25,55}.100=10,95\%\)
\(\%m_{Zn}=100\%-10,95\%=89,05\%\)
b.\(n_{HCl}=2.0,05+2.0,35=0,8mol\)
\(C_M=\dfrac{n}{V}\Rightarrow V=\dfrac{n}{C_M}=\dfrac{0,8}{2}=0,4l\)
Bài 1:
\(n_{HCl}=2.0,16=0,32\left(mol\right);n_{H_2}=\dfrac{3,584}{22,4}=0,16\left(mol\right)\)
PTHH: Mg + 2HCl → MgCl2 + H2
PTHH: Fe + 2HCl → FeCl2 + H2
\(m_{H_2}=0,16.2=0,32\left(g\right)\)
\(m_{HCl}=0,32.36,5=11,68\left(g\right)\)
Theo ĐLBTKL ta có: \(m_{MgCl_2+FeCl_2}=1,4+11,68-0,32=12,76\left(g\right)\)
Bài 12:
Theo ĐLBTKL, ta có:
\(m_{hhkl}+m_{O_2}=m_{hh.oxit}\\ \Leftrightarrow11,9+m_{O_2}=18,3\\ \Leftrightarrow m_{O_2}=18,3-11,9=6,4\left(g\right)\\ n_{O_2}=\dfrac{6,4}{32}=0,2\left(mol\right)\\ V_{O_2\left(đktc\right)}=0,2.22,4=4,48\left(l\right)\)
a)
Gọi số mol Mg, Al là a, b (mol)
=> 24a + 27b = 26,25 (1)
\(n_{H_2}=\dfrac{30,8}{22,4}=1,375\left(mol\right)\)
PTHH: Mg + 2HCl --> MgCl2 + H2
a-->2a--------->a------>a
2Al + 6HCl --> 2AlCl3 + 3H2
b---->3b------->b------>1,5b
=> a + 1,5b = 1,375 (2)
(1)(2) => a = 0,25 (mol); b = 0,75 (mol)
=> \(\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,25.24}{26,25}.100\%=22,857\%\\\%m_{Al}=\dfrac{0,75.27}{26,25}.100\%=77,143\%\end{matrix}\right.\)
b)
nHCl = 2a + 3b = 2,75 (mol)
=> mHCl = 2,75.36,5 = 100,375 (g)
=> \(m_{dd.HCl}=\dfrac{100,375.100}{10}=1003,75\left(g\right)\)
c)
mdd sau pư = 1003,75 + 26,25 - 1,375.2 = 1027,25 (g)
\(\left\{{}\begin{matrix}C\%_{MgCl_2}=\dfrac{0,25.95}{1027,25}.100\%=2,312\%\\C\%_{AlCl_3}=\dfrac{0,75.133,5}{1027,25}.100\%=9,747\%\end{matrix}\right.\)
Gọi \(\left\{{}\begin{matrix}n_{Zn}=a\left(mol\right)\\n_{Fe}=b\left(mol\right)\\n_{Al}=c\left(mol\right)\end{matrix}\right.\) => 65a + 56b + 27c = 10,65 (1)
PTHH: Zn + 2HCl --> ZnCl2 + H2
Fe + 2HCl --> FeCl2 + H2
2Al + 6HCl --> 2AlCl3 + 3H2
=> \(n_{H_2}=a+b+1,5c=\dfrac{5,04}{22,4}=0,225\left(mol\right)\) (2)
PTHH: Zn + Cl2 --to--> ZnCl2
2Fe + 3Cl2 --to--> 2FeCl3
2Al + 3Cl2 --to--> 2AlCl3
=> \(n_{Cl_2}=a+1,5b+1,5c=\dfrac{5,6}{22,4}=0,25\left(mol\right)\) (3)
(1)(2)(3) => \(\left\{{}\begin{matrix}a=0,1\left(mol\right)\\b=0,05\left(mol\right)\\c=0,05\left(mol\right)\end{matrix}\right.\) => \(\left\{{}\begin{matrix}m_{Zn}=0,1.65=6,5\left(g\right)\\m_{Fe}=0,05.56=2,8\left(g\right)\\m_{Al}=0,05.27=1,35\left(g\right)\end{matrix}\right.\)
a) \(\left\{{}\begin{matrix}\%m_{Zn}=\dfrac{6,5}{10,65}.100\%=61,033\%\\\%m_{Fe}=\dfrac{2,8}{10,65}.100\%=26,291\%\\\%m_{Al}=\dfrac{1,35}{10,65}.100\%=12,676\%\end{matrix}\right.\)
b) nHCl = 2a + 2b + 3c = 0,45 (mol)
=> mHCl = 0,45.36,5 = 16,425 (g)
=> \(a\%=C\%=\dfrac{16,425}{200}.100\%=8,2125\%\)
c) mdd sau pư = 10,65 + 200 - 0,225.2 = 210,2 (g)
=> \(\left\{{}\begin{matrix}C\%_{ZnCl_2}=\dfrac{0,1.136}{210,2}.100\%=6,47\%\\C\%_{FeCl_2}=\dfrac{0,05.127}{210,2}.100\%=3,02\%\\C\%_{AlCl_3}=\dfrac{0,05.133,5}{210,2}.100\%=3,176\%\end{matrix}\right.\)
\(n_{H_2}=0,1(mol)\\ \text{Bảo toàn H}\\ n_{H_SO_2}=n_{H_2}=0,1(mol)\\ BTKL:\\ m_{hh}+m_{HCl}=m_{muối}+m_{H_2}\\ 3,28+0,1.36,5=m_{muối}+0,1.2\\ m_{muối}=6,73(g)\)