Answer:
water molecules
Explanation:
Redox reactions are carried out under acidic or basic conditions as the case may be.
If the reaction is carried out in an acid medium, then we must balance the hydrogen ions on the lefthand side of the reaction equation with water molecules on the righthand side of the reaction equation.
For instance, the equation for reduction of MnO4^- under acidic condition is shown below;
MnO4^-(aq) + 5e + 8H^+(aq) --------> Mn^2+(aq) + 4H2O(l)
