Al2(SO4)3
-raport atomic Al:S:O=4:6:24=2:3:12
-raport de masa mAl:mS:mO=108:192:384=54:96:192(simplifica)
-compoziția procentuală:
in 684 g Al2(SO4)3......108g Al... 192g S...384g O
in 100 g Al2(SO4)3....... x........ y......z
x=15,78% Al
y=28,07% S
z=56,14% O