Chapter 5: Stored Energy and Batteries
Energizer Bunny

Energy cannot be created or destroyed, but it can be saved in various forms. One way to store it is in the form of chemical energy in a battery. When connected in a circuit, a battery can produce electricity.

If you look at a battery, it will have two ends &emdash; a positive terminal and a negative terminal. If you connect the two terminals with wire, a circuit is formed. Electrons will flow through the wire and a current of electricity is produced.

Inside the battery, a reaction between the chemicals takes place. But reaction takes place only if there is a flow of electrons. Batteries can be stored for a long time and still work because the chemical process doesn't start until the electrons flow from the negative to the positive terminals through a circuit.

 How the Chemical Reaction Takes Place in a Battery

A very simple modern battery is the zinc-carbon battery, called the carbon battery for short.

This battery contains acidic material within and a rod of zinc down the center. Here's where knowing a little bit of chemistry helps.

When zinc is inserted into an acid, the acid begins to eat away at the zinc, releasing hydrogen gas and heat energy. The acid molecules break up into its components: usually hydrogen and other atoms. The process releases electrons from the Zinc atoms that combine with hydrogen ions in the acid to create the hydrogen gas.

If a rod of carbon is inserted into the acid, the acid does nothing to it.

But if you connect the carbon rod to the zinc rod with a wire, creating a circuit, electrons will begin to flow through the wire and combine with hydrogen on the carbon rod. This still releases a little bit of hydrogen gas but it makes less heat. Some of that heat energy is the energy that is flowing through the circuit.

The energy in that circuit can now light a light bulb in a flashlight or turn a small motor. Depending on the size of the battery, it can even start an automobile.

Eventually, the zinc rod is completely dissolved by the acid in the battery, and the battery can no longer be used.

For a "great" on-line page about batteries, visit the Energizer Learning Center.

 Different Types of Batteries
 Food – Another Method of Storing Energy

Next chapter is about Generators, Turbines and Power Plants.

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