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a)
Gọi \(\left\{{}\begin{matrix}n_{Fe}=a\left(mol\right)\\n_{Mg}=b\left(mol\right)\end{matrix}\right.\)
=> 56a + 24b = 18,4 (1)
PTHH: Fe + 2HCl --> FeCl2 + H2
a-->2a------>a------>a
Mg + 2HCl --> MgCl2 + H2
b--->2b------->b------>b
=> \(a+b=\dfrac{11,2}{22,4}=0,5\) (2)
(1)(2) => a = 0,2 (mol); b = 0,3 (mol)
\(\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{0,2.56}{18,4}.100\%=60,87\%\\\%m_{Mg}=\dfrac{0,3.24}{18,4}.100\%=39,13\%\end{matrix}\right.\)
b) \(n_{HCl\left(pư\right)}=2a+2b=1\left(mol\right)\)
=> \(n_{HCl\left(tt\right)}=\dfrac{1.125}{100}=1,25\left(mol\right)\)
=> mHCl(tt) = 1,25.36,5 = 45,625 (g)
=> \(a=\dfrac{45,625.100}{18,25}=250\left(g\right)\)
c)
mdd sau pư = 18,4 + 250 - 0,5.2 = 267,4 (g)
\(C\%_{FeCl_2}=\dfrac{0,2.127}{267,4}.100\%=9,5\%\)
\(C\%_{MgCl_2}=\dfrac{0,3.95}{267,4}.100\%=10,66\%\)
Sửa: $V_{H_2}=7,168(l)$
$a\bigg)$
Đặt $n_{Mg}=x;n_{Fe}=y;n_{Al}=z$
$\to 24x+56y+27z=9,52(1)$
$n_{H_2}=\dfrac{7,168}{22,4}=0,32(mol)$
$n_{Cl_2}=\dfrac{8,064}{22,4}=0,36(mol)$
BTe: $x+y+1,5z=n_{H_2}=0,32(2)$
BTe: $x+1,5y+1,5z=n_{Cl_2}=0,36(3)$
Từ $(1)(2)(3)\to x=0,12(mol);y=0,08(mol);z=0,08(mol)$
$\to \begin{cases} \%m_{Mg}=\dfrac{0,12.24}{9,52}.100\%=30,25\%\\ \%m_{Fe}=\dfrac{0,08.56}{9,52}.100\%=47,06\%\\ \%m_{Al}=100-47,06-30,25=22,69\% \end{cases}$
$b\bigg)$
Bảo toàn H: $n_{HCl}=2n_{H_2}=0,64(mol)$
$\to C_{M_{HCl}}=\dfrac{0,64}{0,2}=3,2M$
$\to a=3,2$
$c\bigg)$
Dung dịch sau gồm $MgCl_2,FeCl_2,AlCl_3$
Bảo toàn $Mg,Al,Fe:n_{MgCl_2}=0,12(mol);n_{AlCl_3}=n_{FeCl_2}=0,08(mol)$
$\to C_{M_{MgCl_2}}=\dfrac{0,12}{0,2}=0,6M$
$\to C_{M_{AlCl_3}}=C_{M_{FeCl_2}}=\dfrac{0,08}{0,2}=0,4M$
$a\bigg)$
Đặt $n_{Mg}=x;n_{Fe}=y;n_{Al}=z$
$\to 24x+56y+27z=9,52(1)$
$n_{H_2}=\dfrac{14,336}{22,4}=0,64(mol)$
$n_{Cl_2}=\dfrac{8,064}{22,4}=0,36(mol)$
BTe: $x+y+1,5z=n_{H_2}=0,64(2)$
BTe: $x+1,5y+1,5z=n_{Cl_2}=0,36(3)$
Từ $(1)(2)(3)\to$ nghiệm âm, xem lại đề
\(n_{Fe}=a\left(mol\right),n_{Mg}=b\left(mol\right)\)
\(m_{hh}=56a+24b=10.16\left(g\right)\)
\(n_{H_2}=\dfrac{5.6}{22.4}=0.25\left(mol\right)\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(n_{H_2}=a+b=0.25\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.13,b=0.12\)
\(m_{Fe}=0.13\cdot56=7.28\left(g\right)\)
\(m_{Mg}=0.12\cdot24=2.88\left(g\right)\)
\(n_{HCl}=2\cdot n_{H_2}=2\cdot0.25=0.5\left(mol\right)\)
\(C_{M_{HCl}}=\dfrac{0.5}{0.5}=1\left(M\right)\)
$a)$
Đặt $n_{Al}=x(mol);n_{Fe}=y(mol)$
$\to 27x+56y=13,75(1)$
Bảo toàn e: $1,5x+y=n_{H_2}=\dfrac{11,2}{22,4}=0,5(2)$
Từ $(1)(2)\to x=0,25(mol);y=0,125(mol)$
$\to \%m_{Al}=\dfrac{0,25.27}{13,75}.100\%\approx 49,09\%$
$\to \%m_{Fe}=100-49,09=50,91\%$
$b)$
Bảo toàn H: $n_{HCl}=2n_{H_2}=1(mol)$
$\to a=\dfrac{1.36,5.120\%}{18,25\%}=240(g)$
$c)$
Bảo toàn Al,Fe: $n_{AlCl_3}=0,25(mol);n_{FeCl_2}=0,125(mol)$
$m_{dd_{HCl(p/ứ)}}=\dfrac{1.36,5}{18,25\%}=200(g)$
Ta có $m_{dd\, sau}=13,75+200-0,5.2=212,75(g)$
$\to \begin{cases} C\%_{AlCl_3}=\dfrac{0,25.133,5}{212,75}.100\%=15,69\%\\ C\%_{FeCl_2}=\dfrac{0,125.127}{212,75}.100\%=7,46\% \end{cases}$
Mg+2HCl->MgCl2+H2
x------2x--------x---------x
2Al+6HCl->2AlCl3+3H2
y---------3y-----y--------3\2y
ta có :
\(\left\{{}\begin{matrix}24x+27y=11,7\\x+\dfrac{3}{2}y=0,6\end{matrix}\right.\)
=>x=0,15 mol, y=0,3 mol
=>%mMg=\(\dfrac{0,15.24}{11,7}.100=30,77\%\)
=>%mAl=100-30,77=69,23%
b)
m HCl=1,2.36,5=43,8g
=>C%=\(\dfrac{43,8}{200}.100\)=21,9%
Đặt \(\left\{{}\begin{matrix}n_{Mg}=a\left(mol\right)\\n_{Fe}=b\left(mol\right)\\n_{Zn}=c\left(mol\right)\\n_{Al}=d\left(mol\right)\end{matrix}\right.\) \(\Rightarrow95a+127b+136c+133,5d=40,45\) (1)
Sau p/ứ với Clo, ta được: \(95a+162,5b+136c+133,5d=44\) (2)
Lấy PT (2) trừ PT (1) \(\Rightarrow35,5b=3,55\) \(\Rightarrow b=n_{Fe}=0,1\left(mol\right)\)
\(\Rightarrow\%m_{Fe}=\dfrac{0,1\cdot56}{13,47}\cdot100\%\approx41,57\%\)
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: \(n_{HCl}=2n_{H_2}=0,5\left(mol\right)\Rightarrow C_{M_{HCl}}=\dfrac{0,5}{0,2}=2,5\left(M\right)\)
