The dichromate ion ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ and chromate ion ${\mathrm{CrO}}_4^{2-}$ exist in equilibrium, like this:

$\underset{\mathrm{orange}}{{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\rightleftharpoons \underset{\mathrm{yellow}}{2{\mathrm{CrO}}_4^{2-}}\left(\mathrm{aq}\right)+2{\mathrm{H}}^{+}\left(\mathrm{aq}\right)$

What would you see if you added dilute acid to a solution containing chromate ions?