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Reading Selection, Lesson 20

Car Battery or Chemical Factory?

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Car battery

Car batteries store energy. During a chemical reaction, this chemical energy is transformed into electrical energy.

Have you ever wondered where the electricity in batteries comes from? How is it possible to store electricity? If you look inside a battery, you can't see electricity! Perhaps the inquiry on the electrolysis of water holds a clue to answering these questions.

In the experiment on the electrolysis of water, you used electrical energy to produce a chemical reaction—splitting the water into hydrogen and oxygen. A battery does the reverse: It uses a chemical reaction to produce an electric current. A battery stores energy as chemical energy. When a battery is connected to a complete electrical circuit, it releases its stored energy in the form of electricity. A car battery is not part of a complete electrical circuit until a key is turned in the ignition. Once the key is turned, the electrical circuit is complete, causing a chemical reaction to take place in the car battery. Sulfuric acid and plates of lead metal and lead oxide react to form lead sulfate. During this process, electricity is produced.

Person using cell phone.

There are many other types of rechargeable batteries (including the one in this cell phone). All of them release electrical energy through chemical reactions.

Car batteries rarely die, because once the car is started, a generator attached to the engine continually recharges the battery. During recharging, electricity flows through the battery in the opposite direction, reversing the chemical reaction. Car batteries, unlike the batteries used in flashlights and boom boxes, can be recharged thousands of times before they need to be replaced.







Labeled illustration of a car battery

The inside of a car battery is like a chemical factory. Chemical energy is stored and then released as electrical energy. What are the reactants and products of this chemical reaction?


1. Find out the differences between various types of batteries, for example, AA, AAA, 9-volt, lithium ion.

2. Conduct a web search to find out about solar and/or fuel cell cars and how they operate.


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