Empirical Formula of an Oxide of Iron:

To determine the empirical formula of an oxide of iron, we need to calculate the ratio of iron to oxygen atoms in the compound using the given percentages of each element.

Given Information:
- 69.9% iron
- 30.1% dioxygen

Step 1: Convert percentages to grams:
Assuming we have 100 grams of the compound, we can calculate the amount of iron and oxygen present.

Iron:
69.9% of 100g = 69.9g

Oxygen:
30.1% of 100g = 30.1g

Step 2: Convert grams to moles:
Using the molar masses of iron and oxygen, we can convert the grams to moles.

Iron:
Molar mass of iron (Fe) = 55.845 g/mol
Moles of iron = 69.9g / 55.845 g/mol = 1.25 mol

Oxygen:
Molar mass of oxygen (O) = 16.00 g/mol
Moles of oxygen = 30.1g / 16.00 g/mol = 1.88 mol

Step 3: Find the simplest ratio:
Divide the number of moles of each element by the smallest number of moles to find the simplest ratio.

Iron: 1.25 mol / 1.25 mol = 1
Oxygen: 1.88 mol / 1.25 mol = 1.504

Step 4: Round to the nearest whole number:
Since we need the empirical formula to have whole numbers, we round the ratio to the nearest whole number.

Iron: 1
Oxygen: 2

Step 5: Write the empirical formula:
The empirical formula of the oxide of iron is FeO, indicating that it contains one iron atom and two oxygen atoms.

Explanation:
The empirical formula represents the simplest whole number ratio of atoms in a compound. In this case, the ratio of iron to oxygen atoms is 1:2, which is consistent with the empirical formula FeO. This means that for every one iron atom, there are two oxygen atoms in the compound. The percentages of iron and oxygen provided are used to determine the amount of each element in grams, which is then converted to moles using their respective molar masses. By finding the simplest ratio of moles, we can determine the empirical formula of the compound.