For oxidation and reduction reactions, it is important to identify which element is being oxidized and which is being reduced. Using the mnemonic "OIL RIG" will help in this aspect. "Oxidation is loss and reduction is gain" will correctly help in this equation. The fluorine will lose electrons, so it is being oxidized, while the cobalt +2 will be gaining electrons, which means it will be reduced. The two half equations are 2F + 2e- ---> 2F- and Co+2 ---> Co + 2e-. The balanced redox equation is F2 + 2e- + Co+2 ---> CoF2. The cell potential for this reaction is 159 kj mol-1 to break apart the F2 and 435 kj mol-1 per CoF combination, so 2 times that would be 870 kj mol-1. Subtracting the 159 from the 870 would give a net energy exchange of 711 kj mol-1 on the products side of the equation. Since there is a lot of energy given off by the formation of the product, this reaction is very spontaneous.