While trace impurities of iron and chromium in natural corundum form the gemstones ruby and sapphire, they are basically a binary compound of aluminum and oxygen, with 52.9% Al. Find the empirical formula and give the chemical name for corundum.

the answer is Al2O2
but i don't get it

No, it's Al2O3.

Post your work and I'll find the error.
I suspect you rounded 1 to 1.5 to 2:2 whereas 1:1.5 is 2:3. Rounding a fraction that much is not acceptable.

To determine the empirical formula of a compound, we need to find the simplest whole number ratio of the elements present in the compound. In the case of corundum, we are told that it is a binary compound of aluminum (Al) and oxygen (O), and it contains 52.9% aluminum.

To find the empirical formula, we can assume that we have 100 grams of the compound. This means that 52.9 grams of it is aluminum.

Next, we need to determine the number of moles for each element. We can do this by dividing the mass of each element by its molar mass. The molar mass of aluminum is approximately 26.98 g/mol, and the molar mass of oxygen is approximately 16.00 g/mol.

For aluminum:
Number of moles of aluminum = 52.9 g / 26.98 g/mol = 1.96 mol

For oxygen:
Number of moles of oxygen = (100 g - 52.9 g) / 16.00 g/mol = 3.17 mol

Finally, we need to find the simplest whole number ratio of the moles of aluminum and oxygen.

Divide the moles by the smallest value (1.96 mol) to get the ratio:

Aluminum = 1.96 mol / 1.96 mol = 1
Oxygen = 3.17 mol / 1.96 mol ≈ 1.62

To get whole numbers, we can multiply both numbers by 2:

Aluminum = 1 * 2 = 2
Oxygen = 1.62 * 2 ≈ 3.24 ≈ 3

Therefore, the empirical formula for corundum is Al2O3, which means it consists of two aluminum atoms and three oxygen atoms.

The chemical name for corundum is also known as aluminum oxide.