Electrolytes: Conductors of Electricity

1. Electrolytes: Conductors of Electricity Discovering the hidden secrets of lemons!

2. Purpose • To observe properties of an electrolyte in a natural system

3. Demonstration • In this demonstration a copper and zinc electrode are inserted into a lemon and a multimeter is used to measure voltage

4. Concepts • Electricity • Electrolytes • Electrodes • Anode • Cathode

5. Electricity • Electricity – the flow of electrons in a closed circuit.

6. Electrolytes • Are ions that carry the electrons • In this demonstration there are electrolytes in the juice of the lemon that carry the charge. These electrolytes are found in the fruit and include the fruit juice and various ions in it such as sodium and potassium ions, and citric acid as well as other fruit acids

7. Electrodes • An electrode is simply a site where electrons are either lost or gained. • There are two kinds of electrodes: cathodes and anodes. • Cathode is the site at which reduction occurs. Reduction is the gain of electrons. Copper is the cathode. • Anode is the site at which oxidation occurs. Oxidation is the loss of electrons. Zinc is the anode.

8. Conclusion • The space between the two wires is bridged when the multimeter completes the circuit. A noticeable voltage is detected. Voltage measures the potential difference between electrodes. Hooking the lemons up in a series from 1 to 2 to 3 lemons results in a higher voltage. The electrolytes in the lemons complete the circuit—the lemons themselves act as wires which use their electrolytes to carry the electrons.

9. Comments • The original intent of this experiment was to demonstrate electrical properties of a lemon using a small lightbulb. However, due to the small and nearly insignificant current it would take numerous lemons, or a much larger zinc electrode to light a single 25 microAmp bulb.