Final answer:
To find the empirical formula of a compound, convert the masses of potassium, chlorine, and oxygen to moles, find the ratio, and express it as the empirical formula, which in this case is KClO3.
Step-by-step explanation:
To find the empirical formula of a compound using the masses of its elements, first calculate the moles of each element in the sample. For potassium (K), divide the mass of potassium in the sample (5.39 g) by its atomic mass (39.10 g/mol) to get the number of moles of K. Perform the same calculation for chlorine (Cl), dividing its mass (4.89 g) by its atomic mass (35.45 g/mol). For oxygen (O), subtract the mass of K and Cl from the total sample mass to get the mass of O, and then divide by its atomic mass (16.00 g/mol).
After calculating the moles of each element, determine the simplest whole number ratio of the moles of each element. This will provide the empirical formula. If necessary, multiply the ratios by a common factor to get whole numbers.
Example:
For the given masses, the moles of each element would be:
- K: 5.39 g / 39.10 g/mol = 0.138 moles
- Cl: 4.89 g / 35.45 g/mol = 0.138 moles
- O: (16.89 g - 5.39 g - 4.89 g) / 16.00 g/mol = 0.405 moles
The ratio of K:Cl:O in moles is approximately 1:1:3. Therefore, the empirical formula is KClO3.