Lemon Battery

How it works- the chemistry behind it

Batteries are a store of chemical energy that is quickly converted into electrical energy when the battery is wired up. Most batteries contain reactive metals. These metals give up electrons. A simple lemon battery can be constructed using a lemon, iron nail, a copper strip, wire and a galvanometer. This setup is shown on the right.

The needle on the galvanometer is deflected when the wires are connected indicating that electrons are flowing from the iron nail to the copper.

What is happening?
In a lemon battery, both oxidation and reduction reactions occur. Oxidation is a reaction that produces electrons while reduction is a reaction that uses up electrons.

The electrode where oxidation takes place is negative and is called the anode. It is the site of electron production.

The electrode where reduction takes place is positive and is called the cathode. It is the site where electrons are used.

At the anode, metallic zinc is oxidized, and enters the acidic solution as Zn2+ ions:

Zn → Zn2+ + 2e-.

At the copper cathode, hydrogen ions are reduced to form molecular hydrogen:

2H++ 2e- → H2.


1) Electrons travel around an

2) Electrons are given away by the

3) Electrons are taken by the

4) What is formed at the anode

5) What is formed at the cathode

6) An oxidation reaction involves

7) Oxidation always occurs at the

8) Reduction occurs at the

9) The negative terminal is called the

10) The positive terminal is called the

11) The lemon battery will continue to produce a current of electrons until

12) Why would a more reactive metal produce a greater current?