Mg + H2SO4 → MgSO4 + H2 (1)
MgO + H2SO4 → MgSO4 + H2O (2)
\(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
Theo PT1: \(n_{Mg}=n_{H_2}=0,1\left(mol\right)\)
\(\Rightarrow m_{Mg}=0,1\times24=2,4\left(g\right)\)
\(\Rightarrow m_{MgO}=4,4-2,4=2\left(g\right)\)
\(\Rightarrow\%m_{Mg}=\dfrac{2,4}{4,4}\times100\%=54,55\%\)
\(\%m_{MgO}=\dfrac{2}{4,4}\times100\%=45,45\%\)