A compound is 69.9% iron and 30.1% oxygen by mass. What is its empirical formula?

Answer 1

To determine the empirical formula, we need to find the ratio of iron atoms to oxygen atoms in the compound.

First, assume that we have 100 grams of the compound. This means that 69.9 grams is iron and 30.1 grams is oxygen.

Next, we need to find the moles of each element. We can do this by dividing the mass by the molar mass:

- Moles of iron = 69.9 g / 55.85 g/mol = 1.25 mol
- Moles of oxygen = 30.1 g / 16.00 g/mol = 1.88 mol

Now we need to find the simplest whole-number ratio of these moles. We can do this by dividing both moles by the smaller value:

- 1.25 mol / 1.25 mol = 1
- 1.88 mol / 1.25 mol ≈ 1.5

We can round this to the nearest whole number, which gives us a ratio of 1 iron atom to 2 oxygen atoms. Therefore, the empirical formula of this compound is FeO2.