# Determine the Molecular Formula of an Oxide of Iron in Which the Mass Percent of Iron and Oxygen Are 69.9 and 30.1 Respectively

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Updated on: September 25th, 2023

The molecular formula of an oxide of iron in which the mass percent of iron and oxygen are 69.9 and 30.1 respectively is 1.

Since 100 grammes of iron oxide contain 69.9% and 30.1% respectively of iron and oxygen.

Step 1 – Let us find the number of moles

No. of moles of iron present in 100 gram of iron oxide = weight in grams (iron)/ molecular weight of iron = 69.9/55.8 = 1.25 mole

No. of moles of oxygen present in 100 gram of iron oxide = weight in grams (oxygen)/ molecular weight of oxygen = 30.1/16 = 1.88 moles

Step 2: Calculate the ratio of the amount of iron to the amount of oxygen.

Ratio of iron to oxygen = 1.25/1.88 = 1/1.5

By multiplying the ratio with 2 we get ⅔

So the empirical formula of iron oxide is Fe2O3

Step 3 – Let us find n

Empirical mass of Fe2O3 = 2 x 55.85 + 3 x 16 = 159.7

Molar mass of Fe2O3 = 159.69

n = molar mass/ empirical formula mass = 159.69/ 159.7 = 1

### Empirical Formula

1. The empirical formula, which is defined as the ratio of subscripts of the least whole number of the elements present in the formula, is the simplest formula for a compound. The simplest formula is another name for it.
2. The formula of a material expressed with the smallest integer subscript is referred to as an empirical formula for a compound.
3. The empirical formula provides details regarding the ratio of atom counts in the molecule. A compound’s empirical formula is directly related to its % content.

Summary:-

## Determine the Molecular Formula of an Oxide of Iron in Which the Mass Percent of Iron and Oxygen Are 69.9 and 30.1 Respectively

The molecular formula of an oxide of iron in which the mass percent of iron and oxygen are 69.9 and 30.1 respectively is 1

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