Hidroxidul de fier - Fe(OH)3
Raport atomic:
Fe:O:H=1:3:3
Raport de masa:
m Fe:m O: m H=56:3*16:3*1=56:48:3
Compozitia procentuala:
M Fe(OH)3=56+3*16+3*1=107
56 g Fe......48g O.....3 g H...107 g Fe(OH)3
x....................y............z.......100 g Fe(OH)3
x=5600/107=52,34% Fe
y=4800/107=44,86% O
z=300/107=2,8% H