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Ta có: \(n_{Fe_2O_3}=\dfrac{4}{160}=0,025\left(mol\right)\)
a. PTHH: Fe2O3 + 3H2SO4 ---> Fe2(SO4)3 + 3H2O
Theo PT: \(n_{H_2SO_4}=3.n_{Fe_2O_3}=3.0,025=0,075\left(mol\right)\)
=> \(m_{H_2SO_4}=0,075.98=7,35\left(g\right)\)
b. Ta có: 
\(C_{\%_{H_2SO_4}}=\dfrac{7,35}{m_{dd_{H_2SO_4}}}.100\%=9,8\%\)
=> \(m_{dd_{H_2SO_4}}=75\left(g\right)\)
Ta có: \(m_{dd_{Fe_2\left(SO_4\right)_3}}=75+4=79\left(g\right)\)
Theo PT: \(n_{Fe_2\left(SO_4\right)_3}=n_{Fe_2O_3}=0,025\left(mol\right)\)
=> \(m_{Fe_2\left(SO_4\right)_3}=0,025.400=10\left(g\right)\)
=> \(C_{\%_{Fe_2\left(SO_4\right)_3}}=\dfrac{10}{79}.100\%=12,66\%\)
PTHH: \(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\)
a+b) Ta có: \(n_{Fe_2O_3}=\dfrac{16}{160}=0,1\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}n_{HCl}=0,6\left(mol\right)\\n_{FeCl_3}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{ddHCl}=\dfrac{0,6\cdot36,5}{14,6\%}=150\left(g\right)\\m_{FeCl_3}=0,2\cdot162,5=32,5\left(g\right)\end{matrix}\right.\)
\(\Rightarrow C\%_{FeCl_3}=\dfrac{32,5}{150+16}\cdot100\%\approx19,58\%\)
b) PTHH: \(HCl+KOH\rightarrow KCl+H_2O\)
Theo PTHH: \(n_{KOH}=n_{HCl}=0,6\left(mol\right)\) \(\Rightarrow V_{KOH}=\dfrac{0,6}{0,5}=1,2\left(l\right)\)
\(n_{Fe_2O_3}=\dfrac{4}{160}=0,025\left(mol\right)\)
PTHH: Fe2O3 + 3H2SO4 → Fe2(SO4)3 + 3H2O
Mol: 0,025 0,075 0,025
\(m_{ddH_2SO_4}=\dfrac{0,075.98.100}{9,8}=75\left(g\right)\)
mdd sau pứ = 4 + 75 = 79 (g)
\(C\%_{ddFe_2\left(SO_4\right)_3}=\dfrac{0,025.400.100\%}{79}=12,66\%\)
Fe2O3 +3H2SO4----.Fe2(SO4)3 +3H2O
a) Ta có
n\(_{Fe2O3}=\frac{4}{160}=0,025\left(mol\right)\)
Theo pthh
n\(_{H2SO4}=3n_{Fe}=0,075\left(mol\right)\)
m\(_{H2SO4}=0,075.98=7,35\left(g\right)\)
b)m\(_{ddH2SO4}=\frac{7,35.100}{9,8}=75\left(g\right)\)
c) Theo pthh
n\(_{Fe2\left(SO4\right)3}=n_{Fe}=0,025\left(mol\right)\)
m\(_{Fe2\left(SO4\right)3}=0,025.400=10\left(g\right)\)
C%=\(\frac{10}{75+4}=12,66\%\)
Chúc bạn học tốt
\(n_{Zn}=\dfrac{19.5}{65}=0.3\left(mol\right)\)
\(Zn+2HCl\rightarrow ZnCl_2+H_2\)
\(0.3........0.6.........0.3......0.3\)
\(m_{HCl}=0.3\cdot36.5=10.95\left(g\right)\)
\(C\%_{HCl}=\dfrac{10.95}{200}\cdot100\%=5.475\%\)
\(m_{\text{dung dịch sau phản ứng}}=19.5+200-0.3\cdot2=218.9\left(g\right)\)
\(m_{ZnCl_2}=0.3\cdot136=40.8\left(g\right)\)
\(C\%_{ZnCl_2}=\dfrac{40.8}{218.9}\cdot100\%=18.63\%\)
\(M+H_2SO_4\rightarrow MSO_4+H_2\uparrow\\ n_{ASO_4}=n_A=n_{H_2}=n_{H_2SO_4}=a\left(mol\right)\\ 1.m_{ddH_2SO_4}=\dfrac{98a.100}{20}=490a\left(g\right)\\ 2.m_{ddsau}=M_M.a+490a-2a=\left(M_M+488\right).a\left(g\right)\\ C\%_{ddsau}=22,64\%\\ \Leftrightarrow\dfrac{\left(M_M+96\right)a}{\left(M_M+488\right)a}.100\%=22,64\%\\ \Leftrightarrow M_M=18,72\left(loại\right)\)
Khả năng cao sai đề nhưng làm tốt a,b nha
