Help understanding how a battery works.

[johnnyapplese]

I've been trying to understand this but there are some points that lead me to confusion. The first is that a lot of people have been saying the the chemical reaction in the battery starts when you connect the two ends of the terminals to a load. I figured i guess the reaction won't take place unless you connect it to the other end because their is only so much charge the zinc can hold and when you connect the two ends the electricity can escape and the reaction can take place again. If this were the case though shouldn't I be able to attach enough wire to only the negative end and have the electrons escape into that? And also I thought that if if I took something that was an oxidizer such as hydrogen peroxide and attached the negative end of a battery to it, electrons would flow from the wire and react with it. But lacking hydrogen peroxide on hand I thought I would try just salt water. Since salt dissociates into Na+ and Cl- I figured the Na+ would be able to act as an electron acceptor and would take the place of the cathode, but that didn't work when I tried it. I haven't tried the first one but the second one I did so I'm wondering if the first one would happen as I think it would and I'm wondering why the second one didn't.

 

[Vespa71]

The battery gives or takes energy when both terminals are connected in a circuit. The chemical reactions do not occur when there's no flow in AND out, of electrons. Don't think of the battery as a bucket that you can pour electrons in and out of. Try thinking of a hot-water-tank. You can only insert water when you extract water. If you try to extract water, without letting water into the tank, you get vacuum, and no flow.

The battery also need flow, current, to charge/discharge. Forced current into charge, and current forcing out when discharging, but allways connected in a circuit. To charge you need a higher voltage than the battery's unloaded voltage. The battery's energy is not propotional to the number of stored electrons inside, but the weight of intact zink, or whatever material is used, would be propotional. The number of electrons in the battery is constant, whether it is charged or discharged.

 

[Jiggy-Ninja]

There will be some small flow, but it will be very, very small, and very, very brief. It is not continuous, and is due to the small capacitance of the wire. You might be able to get a significant amount of current out into a big enough chunk of metal, but it would need to be HUGE.

The reason that Na and Cl form Na+ and Cl- ions is because it completes their valance shells. An Na+ ion isn't going to accept an atom any more than a Cl- is going to give its up.