Show that chromates and dichromates are interconvertible.

Explanation

The chromate and dichromates are interconvertible in aqueous solution depending upon pH of the solution.
At low pH (acidic medium) :
Chromate converts into dichromate
`2CrO_(4)^(2-)+2H^(+)rarrCr_(2)O_(7)^(2-)+H_(2)O`
At high pH (alkaline medium) :
dichromate is converted into chromate
`Cr_(2)O_(7)^(2-)+2OH^(-)rarr2CrO_(4)^(2-)+H_(2)O`