How would dichromate ion, #Cr_2O_7^(2-)#, oxidize sulfide ion, #S^(2-)#, to give elemental sulfur? The reduction product is #Cr^(2+)#.
Are you sure that the dichromate is reduced to
Normally, we would expect dichromate to give
Sulfide anion is oxidized to elemental sulfur.......:
PS I am not saying you are wrong. I would check your sources or lab manual.
We could formulate reduction to