IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry - how to find oxidation number of central atm???

anil_kapoor

how to find oxidation number of central atom of a complex compound??????
plzzzzzzzzzzzzz help me out...
plzzz...

chimanshu_007

u got to knw the charge on various groups

like on H20 , NH3 its zero

CN -1 etc etc

den its no difficult

anil_kapoor

if its like...
[Cr(C2O4)3]3-
then??????????????/

aditya_arora04

Hi,

Look,

C₂O₄ is oxalate ion, havng a charge of -2.

So, oxidation number of Cr [ denoted by x ]

x-6=-3

x=3

dev_22oct

for that u have to read a chapter called co-ordination chemistry.

few things are imp

1) sum of the oxidation states of a neutral complex is 0

2) sum of the oxidation state of a charged complex is equal to its charge it could be -ve or +ve.

3)read abt ligands like neutal ligand like NH₃ ,H₂O,NO,CO etc they have zero total oxidation state

4)negative ligands, they have total oxidation state equal to their total charge.

eg CL-,Br-

now your example

[Cr(C₂O₄)₃]^3-

Its a negative complex so total oxidation state is equal to -3 thats the total charge.

dev_22oct

since u have to find out oxidation state of Cr put Cr=X

Now calculate

x+ 3(-2)=-3

there fore x=+3 (-2 is the oxidation state of oxalate)

bt dear u have to read that chapter properly.