How to make your own battery
Homemade battery from pencil and bolt
In this experiment, we’ll show you how to make a battery a clock can run on!
Reagents and equipment
- plastic cap;
- graphite rod (pencil graphite);
- silicone tubing;
- 0.5 g graphite powder;
- 0.5 g manganese(IV) oxide;
- cotton absorbent;
- salt solution (ammonium chloride solution, 5 mol/L);
- zinc-plated bolt.
Insert the graphite rod into the plastic cap and attach the construction to the silicone tubing. Add 1 g of a 1:1 mixture of graphite powder and manganese(IV) oxide. Insert the cotton absorbent and add 1 mL of ammonium chloride solution. Insert the zinc-plated bolt. Your battery is ready!
Electrochemical cells are devices in which the energy from chemical reactions is turned into electrical energy. An ordinary battery is an example of a simple electrochemical cell. Its positive terminal consists of manganese(IV) oxide mixed with graphite, its negative terminal consists of metallic zinc, and ammonium chloride acts as its electrolyte (a substance that conducts electricity). When the circuit is closed – for example, when you insert the battery into the clock – an oxidation-reduction reaction begins inside the battery, and electric current begins to flow through the circuit.
The oxidation-reduction reaction goes as follows:
Zn - 2e = Zn²⁺
2MnO₂ + 2NH₄Cl + 2e = Mn₂O₃ + 2NH₃ + H₂O + 2Cl⁻
Such a battery can produce up to 1.5 volts of steady electric current.