When we connect a load to a battery what is the reason of moving electron to load? Is it correct to say because in charging we forced positive ions to placed in anode, when we connect two electrodes with a load they back to their sites in cathode and release electrons at the same time?
The battery does work converting chemical potential energy and giving the charge at its terminals electrical potential energy. Placing a load (a circuit path) across the battery terminals provides the opportunity to convert the electrical potential energy into to motion of the charge in the circuit in response to the force exerted by the electric field produced by the battery.
A rough analogy is gravitational potential energy. If I lift an object a certain height the work I do winds up being stored as gravitational potential energy. The work I do on the object giving it gravitational potential energy is analogous to the work done by the battery on the charge giving it electrical potential energy.
Releasing the object giving it the opportunity to fall is analogous to connecting a circuit to the battery giving the charge the opportunity to move. On the other hand, the motion of the object is not the same as the charge, since the object accelerates in free fall converting the potential energy to kinetic energy, whereas the charge encounters electrical resistance converting at least part of its potential energy into heat dissipated in resistance.
Hope this helps.
It is the redox potential of reactions of two half cells which on joining(load) forms e.m.f. for electrons to flow. Generally reduction potential is considered. Nevertheless positive potential indicates that reaction will occur spontaneously. Commonly used is reduction potential(for reduction reaction of species) if it is positive, species will easily get reduced (from left side species to right side species) and will easily take electron. Not only easily but is eager to take electron. If negative it will not reduce easily and can be oxidised easily. Oxidation potential is negative of reduction potential.
Now reduction occur at cathode so cathode is formed by component who have more positive reduction potential for its reaction. Reaction at cathode will pull the electron and at anode one with low(than cathode) reduction potential is present for negative potential it will leave electron and will generate push for them but if positive potential even if it want to pull electron it have no enough energy to resist cathode and cathode will overcome the anode creating flow.