The
chromate ion is tetrahedral
whereas the dichromate ion
consists of two tetrahedra
sharing one corner with
Cr–O–Cr bond angle of 126° Sodium and potassium dichromates are strong oxidising agents;
the sodium salt has a greater solubility in water and is extensively
used as an oxidising agent in organic chemistry Potassium dichromate
is used as a primary standard in volumetric analysis In acidic solution,
its oxidising action can be represented as follows:
Cr2O7
2– + 14H
+ + 6e
– ® 2Cr
3+ + 7H2O (E
o = 1