\(n_{MgO}=\dfrac{4}{40}=0,1\left(mol\right)\\ PTHH:MgO+2HCl\rightarrow MgCl_2+H_2O\\ \Rightarrow n_{HCl}=2n_{MgO}=0,2\left(mol\right)\\ \Rightarrow m_{CT_{HCl}}=0,2\cdot36,5=7,3\left(g\right)\\ \Rightarrow m_{dd_{HCl}}=\dfrac{7,3\cdot100\%}{7,3\%}=100\left(g\right)\\ n_{MgCl_2}=n_{H_2}=0,1\left(mol\right)\\ \Rightarrow\left\{{}\begin{matrix}m_{CT_{MgCl_2}}=0,1\cdot95=9,5\left(g\right)\\m_{H_2}=0,1\cdot18=1,8\left(g\right)\end{matrix}\right.\\ \Rightarrow m_{dd_{MgCl_2}}=4+100-1,8=102,2\left(g\right)\\ \Rightarrow C\%_{MgCl_2}=\dfrac{9,5}{102,2}\cdot100\%\approx9,3\%\)
\(n_{MgO}=\dfrac{4}{40}=0,1mol\)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\)
0,1 0,2 0,1 0,1
\(m_{HCl}=0,2\cdot36,5=7,3\)
\(m_{ddHCl}=\dfrac{7,3}{7,3}\cdot100=100g\)
\(m_{MgCl_2}=0,1\cdot95=9,5g\)
\(m_{H_2O}=0,1\cdot18=1,8g\)
\(m_{ddsaupu}=4+100-1,8=102,2g\)
\(\%m_{m'}=\dfrac{9,5}{102,2}\cdot100\%=9,3\%\)
