Learn to identify the parts of and be able to describe an electrochemical cell, including the electrolyte, electrodes, anodes, and cathodes. Learn how to make a homemade lemon battery and how to diagram an electrochemical cell that will light a light bulb.
Electrochemistry. This is where the chemical world meets the electrical world. Electrochemistry is when chemical energy is transformed into electrical energy, which is then often transformed into another kind of energy, such as light or heat. It is extremely important to us because of how much electricity we use in our daily lives. Electricity, remember, is the flow of electrons through a path, usually a wire. The whole path is called a circuit.
A flashlight is an example of electrochemistry. Its batteries are undergoing a chemical reaction that transfers chemical energy to electrical energy to light energy.
Parts of an Electrochemical Cell
The parts of an electrochemical cell
The flashlight battery is an electrochemical cell. An electrochemical cell is something that changes chemical energy to electrical energy. It contains two compartments, each with an electrode submerged in an electrolyte. The electrode is just a conductor, usually a metal that connects to a nonmetallic part of a circuit. The electrolyte is a fluid that conducts electricity. One of the plates is positive and one of them is negative. Those two plates are called the cathode and anode, and they're connected by a wire that completes the circuit.
Often, one metal strip in the battery is copper, and it acts as a cathode, which is the electrode where reduction takes place and electrons are gained. The other electrode is the anode, often zinc, where oxidation takes place and electrons are lost. Electrons leave the system from the anode and go into the wire.
So, what happens is the electrons on the anode are lost and travel through the wire to the cathode, where electrons are gained. The solutions the two electrodes are in help conduct the electrons from the surface of the electrode to the wire. The two electrodes are in separate compartments, separated by a porous barrier or salt bridge. The barrier or bridge allows the ions in both solutions to move from one side to the other to prevent charge from building up on the electrodes.
The chemical reaction that occurs in the electrochemical cell is a redox, or reduction-oxidation, reaction. As its name implies, that reaction's made up of two parts: a reduction reaction where electrons are gained and an oxidation reaction where electrons are lost.
Electrochemical Cell Diagram
Electrons move from the anode to the cathode through the wire.
Above you see a two-compartment container filled with an electrolyte solution. On the left side, there is a zinc piece for the electrode. This electrode is the anode because it loses electrons. On the right side is a copper piece for the electrode. This electrode is the cathode because it accepts electrons. Connect the anode to a light bulb with a copper wire. Then connect the light bulb to the cathode with the wire. The circuit is now complete, and the electrons flow from the anode into the light bulb, where it turns into light energy. Then, the electrons go back down the wire into the cathode.
Make a Homemade Battery
How to make a battery out of a lemon
You can make your own battery at home with a lemon, copper pennies and galvanized nails (zinc-coated), a wire, and an LED light. Put the penny in one side of the lemon and the nail in the other side of the lemon. Make sure they don't touch. The nail and the penny are the electrodes, with the nail being negative and the penny being positive. The lemon juice is the electrolyte. Use a wire to connect the nail to an LED and then to the penny. The LED should light up because the circuit is complete. If your LED does not light up, it may be that your penny isn't pure enough copper or the lemon battery isn't strong enough. You can connect lemons in series by connecting one to another with wire to boost the voltage of your battery.
An electrochemical cell is something that changes chemical energy to electrical energy. It consists of two electrodes submerged in an electrolyte that are connected by a wire. The positive electrode is called the cathode and accepts the electrons. The negative electrode is the anode and donates the electrons. The chemical reaction is usually an oxidation-reduction reaction that involves the transfer of electrons from a substance that gets oxidized to a substance that gets reduced.
After this lesson, you'll be able to:
- Define electrochemistry and identify the parts of an electrochemical cell
- Summarize the purpose of the electrolyte in the electrochemical cell
- Explain the functions of the anode and the cathode
- Describe how to make a battery at home using a lemon, penny, nail, wire, and a light