\(PTHH:\text{Al2O3+2NaOH}\rightarrow\text{2NaAlO2+H2O}\)
\(\text{2Al+2NaOH+2H2O}\rightarrow\text{2NaAlO2+3H2}\)
\(\rightarrow nH2=0,3\left(mol\right)\)
\(\rightarrow nAl=0,3.\frac{2}{3}=0,2\left(mol\right)\)
\(\rightarrow mAl=0,2.27=5,4g\)
\(\Rightarrow\text{mAl2O3=10,2}\)