Question

determine a quantidade de mols existentes
a) 500g de Al2 (SO4)3
b)1200g de Fe2(Cr2O7)3
c)1,5Kg de Pb2(CrO4)4
d)2,0kg de CBr4

Answer 1

Para calcular o número de mols usamos:
n=m/MM

a) 500g de Al2(SO4)3
MM=2.27+3.(32+4.16)=342g/mol
m=500g
n=500/342=1,462mol

b) 1200g de Fe2(Cr2O7)3
MM=2.56+3.(2.52+7.16)=760g/mol
m=1200g
n=1200/760=1,579mol

c) 1,5Kg de Pb2(CrO4)4
MM=2.207+4.(52+4.16)=878g/mol
m=1,5kg=1500g
n=1500/878=1,708mol

d) 2,0kg de CBr4
MM=12+4.80=332g/mol
m=2kg=2000g
n=2000/332=6,024mol

Espero ter ajudado =)