a)
\(n_{Al\left(bđ\right)}=\dfrac{9,6}{27}=\dfrac{16}{45}\left(mol\right)\Rightarrow n_{Al\left(pư\right)}=\dfrac{16}{45}.75\%=\dfrac{4}{15}\left(mol\right)\)
PTHH: \(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
Theo PTHH: \(n_{Al_2O_3}=\dfrac{1}{2}.n_{Al\left(pư\right)}=\dfrac{2}{15}\left(mol\right)\Rightarrow m_{Al_2O_3}=\dfrac{2}{15}.102=13,6\left(g\right)\)
b) \(m=m_{Al_2O_3}+m_{Al\left(không.pư\right)}=13,6+27.\left(\dfrac{16}{45}-\dfrac{4}{15}\right)=16\left(g\right)\)