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 \(\Rightarrow\)\(n_{HClpư}=1,2\left(mol\right)\)
\(\Rightarrow n_{HCldư}=\dfrac{654}{365}-1,2=\dfrac{216}{365}\left(mol\right)\)
\(\Rightarrow m_{HCldư}=21,6\left(g\right)\)
\(m_{dd}=32+218=250\left(g\right)\)
\(C\%_{FeCl_3}=\dfrac{65}{250}.100\%=26\left(\%\right)\)
\(C\%_{HCldu}=\dfrac{21,6}{250}.100\%=8,64\%\)