a)\(PTHH:4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
b)\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
\(n_{O_2}=\dfrac{11,2}{22,4}=0,5\left(mol\right)\)
Ta có tỉ lệ:\(\dfrac{n_{Al}}{4}:\dfrac{n_{O_2}}{3}=\dfrac{0,2}{4}< \dfrac{0,5}{3}\Rightarrow\)Al pư hết, O2 pư dư.
Theo PTH ta có:\(n_{Al_2O_3}=\dfrac{2}{4}n_{Al}=\dfrac{2}{4}.0,2=0,1\left(mol\right)\Rightarrow m_{Al_2O_3}=0,1.102=10,2\left(g\right)\)
c)Theo PTHH ta có:\(n_{O_2}\left(pư\right)=\dfrac{3}{4}n_{Al}=\dfrac{3}{4}.0,2=0,15\left(mol\right)\Rightarrow n_{O_2}\left(dư\right)=n_{O_2}-n_{O_2}\left(pư\right)=0,5-0,15=0,35\left(mol\right)\Rightarrow m_{O_2}\left(dư\right)=0,35.32=11,2\left(g\right)\)