Ferric oxide crystallizes in a hexagonal close packed array of oxide with two out of every there octahedral holes occupied by ferric ions.Derive the formula of the ferric oxide.

Ferric oxide crystallizes in a hexagonal close packed array of oxide w

1.	Ferric oxide crystallizes in a hexagonal close packed array of oxide with two out of every there octahedral holes occupied by ferric ions.Derive the formula of the ferric oxide.
Answer» Solution :SUPPOSE the number of oxide IONS ` ( O^(2-))`in the packing =n. No. of OCTAHEDRAL voids =n As 2/3rd of the octahdral voids are occupied by FERRIC ions, therefore, number of ferric ions present ` = 2/3 xx n = (2n)/3` Ratio of ` Fe^(3+): O^(2-) = ( 2n)/3 : n = 2:3 ` Hence, the formula of ferric oxide is ` Fe_(2)O_(3+)`