The overall charge of the reaction is -2. This can be determined by adding up the charges of each individual ion on either side of the reaction.
In this reaction, a total of 6 electrons are transferred. The Cr3+ ion on the reactant side gains 3 electrons to become Cr2O72-, while the Cl- ion on the product side loses 1 electron to become Cl-. This results in a net transfer of 6 electrons.
The oxidation state of Cr changes from +3 in the reactant side (Cr3+) to +6 in the product side (Cr2O72-). This indicates that Cr is oxidized in this reaction.
The Cl- ion is reduced in this reaction. It goes from an oxidation state of 0 in the reactant side to -1 in the product side, indicating a gain of electrons and reduction.
The water molecule acts as a reactant, providing H+ ions that are necessary for the formation of Cl- ions on the product side. Additionally, it helps balance the charges on both sides of the reaction.