Find the oxidation no. of Cr in K2Cr2O7 ?

1 Answer
Apr 15, 2018

#+6#

Explanation:

Potassium dichromate, contains the dichromate ion, in which chromium is in its hexavalent form, i.e. chromium(VI).

We can prove it as follows.

In #K_2Cr_2O_7#, potassium has a #+1# charge, and oxygen has a #-2# charge.

So, the total charge of potassium ions is #+1*2=+2#, while oxygen ions is #-2*7=-14#.

Let #x# be the oxidation number of two chromiums.

So, we got:

#2+x-14=0#

#-12+x=0#

#x=12#

So, two chromium atoms have an oxidation number of #+12#, and so one chromium atom will have an oxidation number of #(+12)/2=+6#.