In the reaction between KI and acidified K2Cr2O7, Cr in the dichromate ion exists in +6 oxidation state. Iodide ions are oxidized to I2 while chromium is reduced. The reduction product is Cr3+ ions, which form chromium(III) salts like Cr2(SO4)3 or coordination complexes. Therefore, the oxidation state of chromium in the final product is +3.