Question

determine molecular mass of an oxide of fe in which the mass % of fe and o are 69.9 and 30.1 respectively. given that molar mass of oxide is 158.8 g/mol ​

Answer 1

Answer:

Explanation:

divide percentage by molar mass

69.6/55.84  30.1/16

1.25  1.88

1 1.5

2 3

fe2o3

empirical mass = 159.68

molar mass = 158.8

molar  mass  / empirical mass = 1 approx

so n factor is 1

so  molecular formula = empirical formula

molecular formula = fe2o3

Answer 2

The iron oxide has 69.9% iron and 30.1% oxygen by mass.
Thus, 100 g of iron oxide contains 69.9 g iron and 30.1 g oxygen
The number of moles of iron present in 100 g of iron oxide are
69.9/55.8=1.25.
The number of moles of dioxygen present in 100 g of iron oxide are
30.1/32=0.94.
The ratio of the number of oxygen atoms to the number of carbon atoms present in one formula unit of iron oxide is
2×0.94/1.25=3:2.
Hence, the formula of the iron oxide is Fe2o3
​