$n_{Al}=\dfrac{8,1}{27}=0,3(mol)$
$\mathop{Al}\limits^0\to \mathop{Al}\limits^{+3}+3e$
$\mathop{S}\limits^{+6}+2e\to \mathop{S}\limits^{+4}$
Bảo toàn e: $3n_{Al}=2n_{SO_2}$
$\to n_{SO_2}= 0,45(mol)$
$\to V_{SO_2}=0,45.22,4=10,08l$
Bảo toàn $Al$: $n_{Al_2(SO_4)_3}=\dfrac{n_{Al}}{2}=0,15(mol)$
$\to m_{Al_2(SO_4)_3}=0,15.342=51,3g$