In a new unconnected battery, has a chemical reaction already occurred to cause excess electrons on anode end? REACTION 1: When I buy a new unconnected alkaline cell, has a chemical reaction already occurred on anode end which releases electrons on anode end?
REACTION 2: Also, in the same new unconnected state of the battery, has a chemical reaction occurred at cathode end that captures electrons from cathode end?
After thinking this through I feel that while REACTION 1 happens in a new unconnected battery, the other REACTION 2 does not occur since there are no free electrons to be captured. If REACTION 2 also did occur in a unconnected new battery then the electrolyte would get all consumed and battery would die pretty soon when connected to an external circuit.
 A: Both reactions have taken place, but involving only an extremely limited number of electrons. At the cathode electrons have been captured from the cathode assembly, including the metal terminal. But relatively few electrons have been captured, and, indeed, relatively few have been released at the anode.
The reason why only relatively few (relative, that is, to the total number of free electrons in the anode and cathode assemblies) are involved is that those on the anode set up an electric field that opposes more electrons arriving and shuts down the reaction. Similarly the positive charge on the cathode assembly opposes more electrons being taken from the cathode assembly and shuts down the cathode reaction.
As you know, all this changes when you provide an external conducting path between cathode and anode: electrons can now escape from the anode assembly and travel through the conducting path to the cathode. So now the reaction at the anode can proceed and electrons are supplied to the cathode so the reaction at that electrode can proceed as well.
