A compound is 69.9% iron and 30.1% oxygen by mass. What is its empirical formula?
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.
To find the empirical formula of a compound, we need to determine the simplest ratio of the atoms present in the compound.
First, let's assume we have 100 grams of the compound.
From the given information, we have:
- 69.9 grams of iron (Fe)
- 30.1 grams of oxygen (O)
Next, we need to find the moles of each element. To do this, we divide the mass of each element by its atomic mass.
The atomic mass of iron (Fe) is 55.85 g/mol.
Moles of iron (Fe) = 69.9 g / 55.85 g/mol ≈ 1.25 mol
The atomic mass of oxygen (O) is 16 g/mol.
Moles of oxygen (O) = 30.1 g / 16 g/mol ≈ 1.88 mol
Next, we need to find the ratio of the atoms. To do this, we divide the number of moles of each element by the smallest number of moles.
Dividing both values by 1.25 (the smallest number of moles), we get:
Fe: 1.25 mol / 1.25 mol = 1
O: 1.88 mol / 1.25 mol ≈ 1.5
The ratio of atoms is approximately Fe1O1.5. However, we need whole numbers for the empirical formula.
To obtain whole numbers, we can multiply both numbers by 2:
Fe: 1 x 2 = 2
O: 1.5 x 2 = 3
Therefore, the empirical formula of the compound is Fe2O3.