2KClO3---->2KCl+3O2
a) n KClO3=30,625/122,5=0,25(mol)
n O2=3/2n KClO3=0,375(mol)
V O2=0,375.22,4=8,4(l)
b) n KCl=n KClO3=0,25(mol)
m KCl=0,25.74,5=18,625(g)
c) 4Al+3O2--->2Al2O3
n Al=10.8/27=0,4(mol)
Do 0,4/4>0,25/3
--->Al dư
n AL2O3=2/3n O2=0,1667(mol)
m Al2O3=0,1667.102=17,0034(g)