What will be the charge of Fe ion ?

Question

An oxide of iron has hcp array of O2- ions with the 2 out of every 3 octahedral voids occupied by Fe ions. Find the formula of the compound. What will be the charge of Fe ion ?

Answer 1

its positive

Answer 2

+2

Answer 3

Go read your lecture notes.

Hexagonal closest packed is the same as face centred cubic.  If you have an fcc lattice of [O]2- ions, how many O ions are in the unit cell?  That's the number of Os you've got in one repeating unit.

How many octahedral holes are there in an fcc lattice?  Multiply by 2/3, that's the number of iron cations in your repeating unit.

Compare the two values.  You'll either have: a 1:1 ratio, which means your formula is FeO so the iron must be Fe(II); a 2:3 ratio, which means that the formula Fe2O3 so the Fe must be Fe(III); some other ratio in which case you messed up some place.

Answer 4

+2,+3

either of them could be there

Answer 5

as it occupy octahedral voids then it must be 2times in no thus formula must be Fe2O3

Answer 6

Ferros and Ferric (both are irons / steel) have different valancies as 2 and 3 respectively. Both have positive charge on ions.