When determining the number of electrons transferred in a redox reaction is it the total in both half equations?
For example:
$$\ce{2I- + Zn^2+ -> I2 + Zn}$$
First we split it up into the two half-reactions and get the following
$$\ce{2I -> I2 + 2e-}$$
$$\ce{Zn^2+ + 2e- -> Zn}$$
So would the number of electrons transferred in the redox reaction be two or four?