Hoà tan hoàn toàn 8 gam hỗn hợp Fe và Fe2O3 bằng dung dịch HCl 10% (d=1,1 g/ml) sau phản ứng thu được 2,24 lit H2 (đktc).
a) Tính thành phần % khối lượng các chất trong hỗn hợp?
b) Tính nồng độ mol/l của các chất trong dung dịch sau phản ứng (coi thể tích dd thay đổi không đáng kể)

.\(a)\)

\(PTHH: Fe + 2HCl ---> FeCl2 + H2\)\((1)\)

\(Fe2O3 + 6HCl ---> 2FeCl3 + 3H2O\) \((2)\)

\(nH2= \dfrac{2,24}{22,4} = 0,1(mol)\)

Theo (1) \(nFe = nH2 = 0,1 (mol)\)

\(=> mFe = 0,1.56 = 5,6 (g)\)

=> %mFe = \(\dfrac{5,6.100}{8}= 70 \)%

=> %mFe2O3 = 100% - 70% = 30%

\(b)\)

mFe2O3 = 8 - 5,6 = 2,4 (g)

=> nFe2O3 = 0,015 (mol)

Theo (1) và (2), nHCl = nHCl(1) + nHCl(2)

<=> nHCl = 0,2 + 0,09 = 0,29 (mol)

=> mHCl = 0,29. 36,5 = 10,585 (g)

Ta có: mddHCl = \(\frac{mHCl.100}{C\%HCl}\) = \(\frac{10,585.100}{10}\) = 105,85 (g)

=> VddHCl = \(\frac{mddHCl}{D_{HCl}}\)= \(\frac{105,85}{1,1}\)= 96,23 (ml)

Đổi 96,23 ml = 0,09623 lit

Theo (1) nFeCl2 = 0,1 (mol)

=> CMFeCl2 = 1,04 M

Theo (2) nFeCl3 = 2.nFe2O3 = 2. 0,015 = 0,03 (mol)

=>CMFeCl3 = 0,3 M

Cách giải a !

a,\(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

PTHH: Fe + 2HCl → FeCl₂ + H₂

Mol:     0,1     0,2         0,1            0,1

PTHH: Fe₂O₃ + 6HCl → 2FeCl₃ + 3H₂O

Mol:     0,05         0,3          0,1     

\(m_{Fe}=0,1.56=5,6\left(g\right);m_{Fe_2O_3}=13,6-5,6=8\left(g\right)\)

\(n_{Fe_2O_3}=\dfrac{8}{160}=0,05\left(mol\right)\)

b,\(m_{HCl}=\left(0,2+0,3\right).98=49\left(g\right)\)

\(m_{ddHCl}=\dfrac{49.100}{10}=490\left(g\right)\)

c,\(m_{ddX}=13,6+490-0,1.2=503,4\left(g\right)\)

d,\(C\%_{FeCl_2}=\dfrac{0,1.127.100\%}{503,4}=2,52\%\)

  \(C\%_{FeCl_3}=\dfrac{0,05.162,5.100\%}{503,4}=1,614\%\)

\(a.Fe+2HCl\rightarrow FeCl_2+H_2\left(1\right)\\ Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\\ n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\\ \Rightarrow n_{Fe}=n_{H_2}=n_{FeCl_2}=0,1\left(mol\right)\\ \Rightarrow\%m_{Fe}=\dfrac{0,1.56}{13,6}.100\approx41,176\%\\ \Rightarrow\%m_{Fe_2O_3}\approx58,824\%\\ b.n_{Fe_2O_3}=\dfrac{13,6-0,1.56}{160}=0,05\left(mol\right)\\ n_{HCl}=2.n_{Fe}+6.n_{Fe_2O_3}=2.0,1+6.0,05=0,5\left(mol\right)\\ m_{ddHCl}=\dfrac{0,5.36,5.100}{10}=182,5\left(g\right)\)

\(c.m_{ddX}=m_{hh\left(Fe,Fe_2O_3\right)}+m_{ddHCl}-m_{H_2}=13,6+182,5-0,1.2=195,9\left(g\right)\\ d.n_{FeCl_3}=2.0,05=0,1\left(mol\right)\\ C\%_{ddFeCl_3}=\dfrac{0,1.162,5}{195,9}.100\approx8,295\%\\ C\%_{ddFeCl_2}=\dfrac{0,1.127}{195,9}.100\approx6,483\%\)

\(n_{H2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Pt : \(Fe+2HCl\rightarrow FeCl_2+H_2|\) 

        1        2               1           1

       0,1     0,2            0,1         0,1

     \(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O|\)

         1            6              2             3

      0,05        0,3            0,1  

a) \(n_{Fe}=\dfrac{0,1.1}{1}=0,1\left(mol\right)\)

\(m_{Fe}=01,.56=5,6\left(g\right)\)

\(m_{Fe2O3}=13,6-5,6=8\left(g\right)\)

⁰/₀Fe =  \(\dfrac{5,6.100}{13,6}=41,18\)⁰/0

⁰/₀Fe₂O₃ = \(\dfrac{8.100}{13,6}=58,82\)⁰/₀

b) \(n_{HCl\left(tổng\right)}=0,2+0,3=0,5\left(mol\right)\)

⇒ \(m_{HCl}=0,5.36,5=18,25\left(g\right)\)

\(m_{ddHCl}=\dfrac{18,25.100}{10}=182,5\left(g\right)\)

c) \(n_{FeCl2}=\dfrac{0,1.1}{1}=0,1\left(mol\right)\)

⇒ \(m_{FeCl2}=0,1.127=12,7\left(g\right)\)

\(n_{FeCl3}=\dfrac{0,3.2}{6}=0,1\left(mol\right)\)

⇒ \(m_{FeCl3}=0,1.162,5=16,25\left(g\right)\)

d) \(m_{ddspu}=13,6+182,5-\left(0,1.2\right)=195,9\left(g\right)\)

\(C_{FeCl2}=\dfrac{12,7.100}{195,9}=6,48\)⁰/₀

\(C_{FeCl3}=\dfrac{16,25.100}{195,9}=8,3\)⁰/₀

 Chúc bạn học tốt

\(Đặt:\left\{{}\begin{matrix}Fe:x\left(mol\right)\\Zn:y\left(mol\right)\end{matrix}\right.\\ Fe+2HCl\rightarrow FeCl_2+H_2\\ Zn+2HCl\rightarrow ZnCl_2+H_2\\ Tacó:\left\{{}\begin{matrix}56x+65y=5,3\\x+y=0,25\end{matrix}\right.\\ \Rightarrow\left\{{}\begin{matrix}x=1,2\\y=-0,97\end{matrix}\right.\left(vô\:lí\right)\)

Em xem lại đề nha!

\(n_{H2}=\frac{2,24}{22,4}=0,1\left(mol\right)\)

Gọi số mol Fe và Fe2O3 là a và b

Ta có \(56a+160b=21,6\)

\(Fe+2HCl\rightarrow FeCl_2+H_2\)

\(Fe_2O_3+6HCl\rightarrow2FeCl_2+3H_2\)

a. \(n_{Fe}=n_{H2}=0,1\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\)

\(\%m_{Fe}=\frac{0,1.56}{21,6}=25,92\%\)

\(\%m_{Fe2O3}=100\%-25,92\%=74,08\%\)

b. \(n_{HCl}=2n_{Fe}+6n_{Fe2O4}=2.0,1+6.0,1=0,8\)

\(\Rightarrow m_{HCl}=0,8.36,5=29,2\)

\(m_{dd_{HCl}}=\frac{29,2}{14,6\%}=200\left(g\right)\)

Khối lượng dd sau phản ứng:

m=m rắn+mddHCl-mH2

\(\Rightarrow m=21,6+200-0,1.2=221,4\left(g\right)\)

\(C\%_{FeCl2}=\frac{0,1.127}{221,4}=5,74\%\)

\(C\%_{FeCl3}=\frac{0,2.162,5}{221,4}=14,68\%\)

\(a) \\ Fe + H_2SO_4 \to FeSO_4 + H_2\\ Fe_2O_3 + 3H_2SO_4 \to Fe_2(SO_4)_3 + 3H_2O\\ b) \text{Theo PTHH} : \\ n_{Fe} = n_{H_2} = \dfrac{2,24}{22,4} = 0,1(mol)\\ \%m_{Fe} = \dfrac{0,1.56}{8} .100\% = 70\%\\ \%m_{Fe_2O_3} = 100\% -70\% = 30\%\)

\(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\\ PTHH:Fe+H_2SO_4\rightarrow FeSO_4+H_2\\ \left(mol\right).....0,1...........................\leftarrow0,1\\ m_{Fe}=0,1.56=5,6\left(g\right)\\ m_{Fe_2O_3}=\Sigma m_{hh}-m_{Fe}=8-5,6=2,4\left(g\right)\\ PTHH:Fe_2O_3+3H_2SO_4\rightarrow Fe_2\left(SO_4\right)_3+3H_2O\\ \left\{{}\begin{matrix}\%m_{Fe}=\dfrac{5,6}{8}.100\%=70\%\\\%m_{Fe_2O_3}=\dfrac{2,4}{8}.100\%=30\%\end{matrix}\right.\)

PTHH: \(Zn+2HCl\rightarrow ZnCl_2+H_2\uparrow\)

            \(Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\)

a) Ta có: \(n_{H_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)=n_{Zn}\)

\(\Rightarrow\%m_{Zn}=\dfrac{0,4\cdot65}{36,2}\cdot100\%\approx71,23\%\) \(\Rightarrow\%m_{Al_2O_3}=28,77\%\)

c) Ta có: \(n_{Al_2O_3}=\dfrac{36,2-0,4\cdot65}{102}=0,1\left(mol\right)\)

Theo PTHH: \(n_{HCl}=2n_{Zn}+6n_{Al_2O_3}=1,4\left(mol\right)\)

\(\Rightarrow m_{ddHCl}=\dfrac{1,4\cdot36,5}{10\%}=511\left(g\right)\) \(\Rightarrow V_{ddHCl}=\dfrac{511}{1,1}\approx464,5\left(ml\right)=0,4645\left(l\right)\)

c) Theo PTHH: \(\left\{{}\begin{matrix}n_{ZnCl_2}=0,4\left(mol\right)\\n_{AlCl_3}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}C_{M_{ZnCl_2}}=\dfrac{0,4}{0,4645}\approx0,86\left(M\right)\\C_{M_{AlCl_3}}=\dfrac{0,2}{0,4645}\approx0,43\left(M\right)\end{matrix}\right.\)

\(n_{H_2}=\dfrac{2,24}{22,4}=0,1(mol)\\ a,Zn+2HCl\to ZnCl_2+H_2\\ b,n_{ZnCl_2}=0,1(mol)\\ \Rightarrow m_{ZnCl_2}=0,1.136=13,6(g)\\ c,n_{Zn}=0,1(mol)\\ \Rightarrow \%_{Zn}=\dfrac{0,1.65}{20}.100\%=32,5\%\\ \Rightarrow \%_{Ag}=100\%-32,5\%=67,5\%\)

áp dụng công thức là ra