1. Electrochemical Cells

2. A battery is a combination of electrochemical cells.
Each electrochemical cell is a package of chemicals that converts chemical energy into electrical energy.

3. Citric acid is an example of an electrolyte
A simple electrochemical cell includes an electrolyte and two electrodes:
An electrolyte is a liquid or paste that conducts electric charge because it contains chemicals that form ions.
Citric acid is an example of an electrolyte
An ion is an atom or a group of atoms that has become electrically charged by losing or gaining electrons.

4. Electrodes are metal strips that react with the electrolyte.
Two different electrodes, such as zinc and copper, are used in a battery.

5. As a result of the reaction between the electrolyte and electrodes, electrons collect on one of the electrodes, making it negatively charged.
The other electrode has lost electrons, so it becomes positively charged.

6. Wet Cells
An electrochemical cell that has a liquid electrolyte is called a wet cell.
Wet cells are often used as an energy source for cars and other motorized vehicles because they are less costly.

7. What benefits would using a paste provide?
Dry Cells
An electrochemical cell that uses a paste instead of a liquid electrolyte is called a dry cell.
What benefits would using a paste provide?

8. anode – negative terminal
Anatomy of Dry Cells
cathode – positive terminal +
carbon electrode – positively charged
zinc electrode – negatively charged
ammonium chloride – electrolyte paste —
anode – negative terminal
Electrodes – provide the electrons for the electrical current.
Electrolyte – helps to transport the electrons between the electrodes.

10. Recycling and Re-energizing Dry Cells
You should always recycle dry cells! They contain toxic materials and heavy metals: nickel, cadmium, and lead.
Household batteries are responsible for over 50% of all the heavy metals found in landfills!

11. Some dry cells can be recharged!
Chemical reactions in a rechargeable cell can be reversed by using an external energy source to run electrical energy back through the cell.
The reversed flow of electrons restores the reactants that are used up when the cell produces electrical energy.