Question

In corundum, oxide ions are arranged in hcp array and the aluminium ions occupy two thirds of octahedral voids. what is the formula of corundum?

Answer 1

Hey !!

Let the number of oxide ions in the paking be N

Then Octahedral voids = N.

Therefore, Al³⁺ ions = 2/3 × N = 2N/3

∴ Ratio of Al³⁺ : O²⁻  = 2N/3 : N = 2:3

Hence, formula of corundum in Al₂O₃

Hope it helps you !!

Answer 2

Answer:

The formula of corundum is Al2O3.