a)\(n_{Fe_2O_3}=0,2\left(mol\right)\)

PT:\(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\)

     \(0,2\)          \(1,2\)          \(0,4\)

\(\Rightarrow n_{FeCl_3}=0,4\left(mol\right)\)

\(\Rightarrow m_{FeCl_3}=65\left(g\right)\)

b) \(n_{HCl}=\dfrac{218.30\%}{35,5+1}=\dfrac{654}{365}\left(mol\right)\)

Từ PT \(\Rightarrow\)\(n_{HClpư}=1,2\left(mol\right)\)

\(\Rightarrow n_{HCldư}=\dfrac{654}{365}-1,2=\dfrac{216}{365}\left(mol\right)\)

\(\Rightarrow m_{HCldư}=21,6\left(g\right)\)

\(m_{dd}=32+218=250\left(g\right)\)

\(C\%_{FeCl_3}=\dfrac{65}{250}.100\%=26\left(\%\right)\)

\(C\%_{HCldu}=\dfrac{21,6}{250}.100\%=8,64\%\)

\(n_{Fe2O3}=\dfrac{16}{160}=0,1\left(mol\right)\)

\(m_{ct}=\dfrac{7,3.400}{100}=29,2\left(g\right)\)

\(n_{HCl}=\dfrac{29,2}{36,5}=0,8\left(mol\right)\)

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

          1             6              2              3

       0,1           0,8            0,2 

Lập tỉ số so sánh : \(\dfrac{0,1}{1}< \dfrac{0,8}{6}\)

               ⇒ Fe₂O₃ phản ứng hết , HCl dư

               ⇒ Tính toán dựa vào số mol của Fe₂O₃

\(n_{FeCl3}=\dfrac{0,1.2}{1}=0,2\left(mol\right)\)

⇒ \(m_{FeCl3}=0,2.162,5=32,5\left(g\right)\)

\(n_{HCl\left(dư\right)}=0,8-\left(0,1.6\right)=0,2\left(mol\right)\)

⇒ \(m_{HCl\left(dư\right)}=0,2.36,5=7,3\left(g\right)\)

\(m_{ddspu}=16+400=416\left(g\right)\)

\(C_{FeCl3}=\dfrac{32,5.100}{416}=7,8125\)⁰/₀

\(C_{HCl\left(dư\right)}=\dfrac{7,3.100}{416}=1,75\)⁰/₀

 Chúc bạn học tốt

a)Theo bài ta có;

\(n_{Fe_2O_3}=\dfrac{m_{Fe_2O_3}}{M_{Fe_2O_3}}=\dfrac{3,2}{160}=0,02\left(mol\right)\)

pthh:\(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\)

số mol__0,2_____1,2

Theo bài và pthh ta có:

\(n_{HCl}=6\cdot n_{Fe_2o_3}=6\cdot0,2=1,2\left(mol\right)\)

\(\Rightarrow m_{HCl}=n_{HCl}\cdot M_{HCl}=1,2\cdot36,5=43,8\left(g\right)\)

\(\Rightarrow C\%=\dfrac{m_{HCl}}{m_{ddHCl}}=\dfrac{43,8}{200}=21,9\%\)

b)

\(m_{HCl}=\dfrac{C\%\cdot m_{ddHCl2,5\%}}{100\%}=\dfrac{2,5\%\cdot200}{100\%}=5\left(g\right)\)

\(\Rightarrow n_{HCl}=\dfrac{m_{HCl}}{M_{HCl}}=\dfrac{5}{36,5}\approx0,137\left(mol\right)\)

Ta có :

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

số mol bđ: 0,2______0,137

số mol tgpư: 0,022_____0,137

số mol dư: 0,178______0

⇒ Sau phản ứng Fe2O3 còn dư,HCl tgpuw hết.

⇒DD sau pư gồm FeCl3 và Fe2O3 dư

Ta có

\(n_{FeCl_3}=\dfrac{1}{3}\cdot n_{HCl}=\dfrac{1}{3}\cdot0,137\approx0.045\left(mol\right)\)

\(\Rightarrow m_{FeCl_3}=n_{FeCl_3}\cdot M_{FeCl_3}=0,045\cdot162,5=7,3125\left(g\right)\)

\(m_{Fe_2O_3dư}=n_{Fe_2O_3dư}\cdot M_{Fe_2O_3}=0,178\cdot160=28,48\left(g\right)\)

\(m_{ddspuw}=m_{Fe_2O_3}+m_{ddHCl}=3,2+200=203,2\left(g\right)\)

\(\Rightarrow C\%_{FeCl_3}=\dfrac{m_{FeCl3}\cdot100\%}{m_{ddspuw}}=\dfrac{7,3125\cdot100\%}{203,2}\approx3,6\%\)

\(\Rightarrow C\%_{Fe2O3dư}=\dfrac{m_{Fe2O3duw}\cdot100\%}{m_{ddspuw}}=\dfrac{28,48\cdot100\%}{203,3}=14,01\%\)

Chúc bạn học tốt

$n_{CuO} = \dfrac{8}{80} = 0,1(mol) ; n_{HCl} = 0,15.2 = 0,3(mol)$
$CuO + 2HCl \to CuCl_2 + H_2O$
Ta thấy : 

$n_{CuO} : 1 < n_{HCl} : 2$ nên HCl dư

$n_{CuCl_2} = n_{CuO} = 0,1(mol)$
$n_{HCl\ pư} = 2n_{CuO} = 0,2(mol) \Rightarrow n_{HCl\ dư} = 0,3 - 0,2 = 0,1(mol)$
$C_{M_{CuCl_2}} = \dfrac{0,1}{0,15} = 0,67M$
$C_{M_{HCl}} = \dfrac{0,1}{0,15} = 0,67M$

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Pls ai giúp mình đi cần gấp lắm

\(n_{Fe_2O_3}=\dfrac{32}{160}=0,2\left(mol\right)\)

\(m_{H_2SO_4}=196.40\%=78,4\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{78,4}{98}=0,8\left(mol\right)\)

PTHH: Fe₂O₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O

Mol:       0,2             0,6              0,2

Ta có: \(\dfrac{0,2}{1}< \dfrac{0,8}{3}\) ⇒ Fe₂O₃ hết, H₂SO₄ dư

m_{dd sau pứ} = 32 + 196 = 228 (g)

\(C\%_{ddFe_2\left(SO_4\right)_3}=\dfrac{0,2.400.100\%}{228}=35,09\%\)

\(C\%_{ddH_2SO_4dư}=\dfrac{\left(0,8-0,6\right).98.100\%}{228}=8,596\%\)