Final answer:
After calculating the mass of oxygen by subtracting the masses of potassium and chlorine from the total sample mass, we convert the masses to moles using their atomic masses. By dividing moles of each element by the smallest mole value obtained and finding a whole number ratio, the empirical formula is determined to be KClO3.
Step-by-step explanation:
The empirical formula of a compound can be calculated using the mass of each element in the sample. The student has a 10.25 g sample containing 3.27 g of potassium (K), 2.97 g of chlorine (Cl), and the remainder being oxygen (O). First, calculate the mass of oxygen in the sample by subtracting the masses of K and Cl from the total mass: (10.25 g - 3.27 g - 2.97 g = 4.01 g of O). Next, convert the masses of K, Cl, and O to moles by dividing by their respective atomic masses (K = 39.10 g/mol, Cl = 35.45 g/mol, O = 16.00 g/mol).
Moles of K = 3.27 g / 39.10 g/mol = 0.0836 mol
Moles of Cl = 2.97 g / 35.45 g/mol = 0.0837 mol
Moles of O = 4.01 g / 16.00 g/mol = 0.2506 mol
Now, find the simplest whole number ratio of moles by dividing each by the smallest number of moles obtained:
- Moles K: 0.0836 mol / 0.0836 mol = 1
- Moles Cl: 0.0837 mol / 0.0836 mol ≈ 1
- Moles O: 0.2506 mol / 0.0836 mol ≈ 3
The empirical formula is therefore KClO3.