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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.\(n_{HCl}=2.0,05+2.0,35=0,8mol\)
\(C_M=\dfrac{n}{V}\Rightarrow V=\dfrac{n}{C_M}=\dfrac{0,8}{2}=0,4l\)
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)
\(\left\{{}\begin{matrix}C\%_{MgCl_2}=\dfrac{0,25.95}{1027,25}.100\%=2,312\%\\C\%_{AlCl_3}=\dfrac{0,75.133,5}{1027,25}.100\%=9,747\%\end{matrix}\right.\)
a, Ta có: 24nMg + 56nFe = 9,2 (g) (1)
\(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)
BT e, có: 2nMg + 2nFe = 2nH2 = 0,5 (2)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,15\left(mol\right)\\n_{Fe}=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,15.24}{9,2}.100\%\approx39,13\%\\\%m_{Fe}\approx60,87\%\end{matrix}\right.\)
b, BTNT H, có: \(n_{HCl}=2n_{H_2}=0,5\left(mol\right)\Rightarrow C_{M_{HCl}}=\dfrac{0,5}{0,2}=2,5\left(M\right)\)
a) Gọi số mol Mg, CuO là a, b (mol)
=> 24a + 80b = 14 (1)
\(n_{HCl}=\dfrac{255,5.10\%}{36,5}=0,7\left(mol\right)\)
PTHH: Mg + 2HCl --> MgCl2 + H2
a--->2a--------->a------>a
CuO + 2HCl --> CuCl2 + H2O
b------>2b----->b
=> 2a + 2b = 0,7 (2)
(1)(2) => a = 0,25 (mol); b = 0,1 (mol)
=> \(\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,25.24}{14}.100\%=42,857\%\\\%m_{CuO}=\dfrac{0,1.80}{14}.100\%=57,143\%\end{matrix}\right.\)
b)
mdd sau pư = 14 + 255,5 - 0,25.2 = 269 (g)
\(C\%_{MgCl_2}=\dfrac{0,25.95}{269}.100\%=8,829\%\)
\(C\%_{CuCl_2}=\dfrac{0,1.135}{269}.100\%=5,019\%\)
a)
Gọi $n_{Zn} = a(mol) ; n_{Al} = b(mol) \Rightarrow 65a + 27b = 11,9(1)$
$Zn + 2HCl \to ZnCl_2 + H_2$
$2Al + 6HCl \to 2AlCl_3 + 3H_2$
Theo PTHH :
$n_{H_2} = a + 1,5b = \dfrac{8,96}{22,4} = 0,4(2)$
Từ (1)(2) suy ra : a = 0,1; b = 0,2
$m_{Zn} = 0,1.65 = 6,5(gam)$
$m_{Al} = 0,2.27 = 5,4(gam)$
b) $n_{HCl} = 2n_{H_2} = 0,8(mol)$
$C\%_{HCl} = \dfrac{0,8.36,5}{125}.100\% = 23,36\%$
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:
\(m_{hhkl}+m_{O_2}=m_{hh.oxit}\\ \Leftrightarrow11,9+m_{O_2}=18,3\\ \Leftrightarrow m_{O_2}=18,3-11,9=6,4\left(g\right)\\ n_{O_2}=\dfrac{6,4}{32}=0,2\left(mol\right)\\ V_{O_2\left(đktc\right)}=0,2.22,4=4,48\left(l\right)\)
\(n_{H_2}=\dfrac{6,72}{22,4}=0,3mol\)
\(\left\{{}\begin{matrix}n_{Mg}=x\left(mol\right)\\n_{Zn}=y\left(mol\right)\end{matrix}\right.\Rightarrow24x+65y=11,3\left(1\right)\)
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(Zn+2HCl\rightarrow ZnCl_2+H_2\)
\(\Rightarrow x+y=0,3\left(2\right)\)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,2mol\\y=0,1mol\end{matrix}\right.\)
a)\(\%m_{Mg}=\dfrac{0,2\cdot24}{11,3}\cdot100\%=42,48\%\)
\(\%m_{Zn}=100\%-42,48\%=57,52\%\)
b)\(n_{HCl}=2\left(n_{Mg}+n_{Zn}\right)=2\cdot\left(0,2+0,1\right)=0,6mol\)
\(C_{M_{HCl}}=\dfrac{0,6}{0,2}=3M\)