Fe2(CO3)3 cu masa moleculara 292g/mol
In 292 g compus exista 6,022*10²³molecule
......14*6,022*10²³ atomi
in 500g compus................ x
molecule....... y atomi
x=........10,31* 10²³ molecule
y=144,36*10²³ atomi
nr. moli de molecule= N/N Avogadro=10,31*10²³/ 6,022*10²³=1,71 moli