Question

Why Are Chromate And Dichromate Anions Colored?

Answer 1

Chromate and Dichromate:

1. Chromate salts include the chromate anion, ${{\mathrm{CrO}}_4}^{2-}$.
2. Dichromate salts include the dichromate anion, ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}.$
3. They are chromium oxyanions in the 6+ oxidation state and are relatively potent oxidising agents.
4. In an aqueous solution, the chromate and dichromate ions can interconvert.

Coloured Chromate And Dichromate Anions are:

1. One of the main reasons for the colouring of chromate and dichromate anions is the presence of transition ions (chromate (vi) ions).
2. Coloured ions are usually produced from transition elements. it is also feasible to argue that the colours we see are complimentary to the vibration wavelength of a bond.
3. The chromate ion contains ${\mathrm{Cr}}^{6+}$. This ion is strongly oxidising due to its high charge, inducing charge transitions in the visible portion of the spectrum, resulting in the colour.
4. The bands are thick and the colour is deep since they have complete orbital permission. Dichromate has two chromium atoms and seven oxide atoms, comparable to chromium oxide (i.e., ${\mathrm{Cr}}_2{\mathrm{O}}_7$).