Bài 19. Cho 22,2 gam hỗn hợp gồm Fe, Al tan hoàn toàn trong HCl, ta thu được 13,44 lít H2 (đktc). Tính thành phần % khối lượng mỗi chất trong hỗn hợp và khối lượng muối clorua khan thu được.
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PTHH:
(1) 2 Al + 6 HCl -> 2AlCl3 + 3 H2
x_____3x_________x_______1,5x (mol)
(2) Fe + 2 HCl -> FeCl2 + H2
y___________2y___y___y (mol)
Ta có: nH2= 13,44/22,4= 0,6(mol)
nH2(1) + nH2(2)= nH2(tổng)
<=> 1,5x+y=0,6 (a)
Ta có: mAl+mFe= 22,2
<=> 27x+56y=22,2 (b)
Từ (a), (b) ta có hpt:
\(\left\{{}\begin{matrix}1,5x+y=0,6\\27x+56y=22,2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0,2\\y=0,3\end{matrix}\right.\)
Ta có: mAl= 0,2.27=5,4(g)
=> %mAl= \(\frac{5,4}{22,2}.100\approx24,324\%\)
=> \(\%mFe\approx100\%-24,324\%\approx75,676\%\)
* nAlCl3= x= 0,2(mol)
nFeCl2= y=0,3(mol)
=> mAlCl3= 133,5.0,2=26,7(g)
mFeCl2= 127.0,3= 38,1(g)
=> %mAlCl3= \(\frac{26,7}{26,7+38,1}.100\approx41,204\%\\ \Rightarrow\%mFeCl2\approx100\%-41,204\%\approx58,796\%\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
Ta có :
\(\left\{{}\begin{matrix}27x+56y=22,2\\1,5x+y=\frac{13,44}{22,4}\end{matrix}\right.\rightarrow\left\{{}\begin{matrix}x=0,2\\y=0,3\end{matrix}\right.\)
\(\rightarrow\%m_{Al}=\frac{0,2.27}{22,2}.100\%=24,32\%,\%m_{Fe}=100\%-24,32\%=75,68\%\)
\(m_{AlCl3}=0,2.133,5=26,7\left(g\right)\)
\(m_{FeCl_2}=0,3.127=38,1\left(g\right)\)
a) \(n_{AlCl_3}=\dfrac{6,675}{133,5}=0,05\left(mol\right)\)
PTHH: 2Al + 6HCl --> 2AlCl3 + 3H2
0,05<-----------0,05---->0,075
=> \(\%Al=\dfrac{0,05.27}{14,15}.100\%=9,54\%\)
=> \(\%Cu=\dfrac{14,15-0,05.27}{14,15}.100\%=90,46\%\)
b) \(V_{H_2}=0,075.22,4=1,68\left(l\right)\)
c) \(n_{Cu}=\dfrac{14,15-0,05.27}{64}=0,2\left(mol\right)\)
PTHH: 4Al + 3O2 --to--> 2Al2O3
0,05->0,0375
2Cu + O2 --to--> 2CuO
0,2-->0,1
=> \(V_{O_2}=\left(0,1+0,0375\right).22,4=3,08\left(l\right)\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\\ m_{AlCl_3}=6,675\left(mol\right)\\ n_{AlCl_3}=\dfrac{6,675}{133,5}=0,05\left(mol\right)\\ \Rightarrow n_{Al}=n_{AlCl_3}=0,05\left(mol\right)\\ \Rightarrow m_A=0,05.27=1,35\left(g\right);m_{Cu}=14,15-1,35=12,8\left(g\right)\\ \%m_{Cu}=\dfrac{12,8}{14,15}.100\approx90,459\%\\ \Rightarrow\%m_{Al}\approx9,541\%\\ b,n_{Cu}=\dfrac{12,8}{64}=0,2\left(mol\right)\\ n_{H_2}=\dfrac{3}{2}.n_{Al}=\dfrac{3}{2}.0,05=0,075\left(mol\right)\\ \Rightarrow V=V_{H_2\left(đktc\right)}=0,075.22,4=1,68\left(l\right)\\ 4Al+3O_2\rightarrow\left(t^o\right)2Al_2O_3\\ 2Cu+O_2\rightarrow\left(t^o\right)2CuO\\ n_{O_2}=\dfrac{3}{4}.n_{Al}+\dfrac{1}{2}.n_{Cu}=\dfrac{3}{4}.0,05+\dfrac{1}{2}.0,2=0,0875\left(mol\right)\)
\(\Rightarrow V_{O_2\left(đktc\right)}=0,0875.22,4=1,96\left(l\right)\)
Đáp án C.
→ n C l - = 2 n H 2 = 0 , 16 → m m u o i = 4 , 34 + 0 , 16 . 35 , 5 = 10 , 02
\(n_{H_2}=\dfrac{13,44}{22,4}=0,6\left(mol\right)\\ \left\{{}\begin{matrix}n_{Fe}=a\left(mol\right)\\n_{Al}=b\left(mol\right)\end{matrix}\right.\left(a,b>0\right)\\ Fe+2HCl\rightarrow FeCl_2+H_2\\ a.......2a........a...........a\left(mol\right)\\ 2Al+6HCl\rightarrow2AlCl_3+3H_2\\ b.........3b.........b........1,5b\left(mol\right)\\ \rightarrow\left\{{}\begin{matrix}56a+27b=22,2\\a+1,5b=0,6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,3\\b=0,2\end{matrix}\right.\\ \%m_{FeCl_2}=\dfrac{0,3.127}{0,3.127+0,2.133,5}.100\approx58,796\%\\ \%m_{AlCl_3}\approx41,204\%\)