The Total solution for NCERT class 6-12
Ferric oxidecrystallises in a hexagonal close-packed array of oxide ions with two out ofevery three octahedral holes occupied by ferric ions. Derive the formula of theferric oxide.
Let the number of oxide(O2−) ions be x.
So, number of octahedralvoids = x
It is given that two outof every three octahedral holes are occupied by ferric ions.
= 2 : 3
Hence, the formula ofthe ferric oxide is Fe2O3.