. Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive


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

Best Answer

There is one octahedral hole for each atom in hexagonal close packed arrangement. If the number of oxide ions (O2-) per unit cell is 1, then the number of Fe3+ ions = 2/3 × octahedral holes = 2/3 × 1 = 2/3. Thus, the formula of the compound = Fe2/3 O1 or Fe2O3.
 

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