Final answer:
The empirical formula for a compound with 0.400 mole of Al and 0.600 mole of O is obtained by finding the simplest whole-number ratio, which is Al2O3, making the correct answer a. Al2O3.
Step-by-step explanation:
The empirical formula for a compound represents the simplest whole-number ratio of the elements within it. Given the mole ratios of 0.400 mole of aluminum (Al) and 0.600 mole of oxygen (O), we can find the empirical formula by following these steps:
- First, divide the number of moles of each element by the smallest number of moles to get the simplest ratio.
- For aluminum: 0.400 mole / 0.400 mole = 1
- For oxygen: 0.600 mole / 0.400 mole = 1.5
- Since we cannot have half of an atom in an empirical formula, we multiply each ratio by 2 to get whole numbers.
- For aluminum: 1 × 2 = 2
- For oxygen: 1.5 × 2 = 3
This yields a ratio of 2 aluminum atoms to 3 oxygen atoms, which means the empirical formula is Al2O3. Therefore, the correct answer is a. Al2O3.