The Science

In a battery, a single cell consists of plates of metal or carbon, which are dipped into ionic solutions also known as electrolyte (Battery, electric, 1983). Pure water has very good conductivity, but it cannot replace the electrolyte because it is also a very good electrical insulator (Battery, electric, 1983). For example, sulphuric acid, when it dissolves into the electrolyte, the molecules split up; the two hydrogen atoms separate and in the process they lose each an electron making the hydrogen atom positively charged. Then the one sulphuric atom and the four oxygen atoms stay in the same form and receive the two lost electrons of the hydrogen atom making the SO4 negatively charged.

If one plate or electrode of zinc and one of either carbon or copper is dipped into a sulphuric acid electrolyte, and each is connected to for example a light bulb,  a electric current will go through and into the bulb, lighting it. The atoms of the zinc each give up two electrons which go through the external circuit and form the current. The positive zinc atoms dissolve into the electrolyte and combines with the negatively charged SO4 resulting in a neutral zinc sulphate molecule. The two released electrons from the zinc travel around the circuit to the other plate (positive plate). There they combine with the two positively charged hydrogen atoms from the electrolyte and neutralize them.

The two neutralized hydrogen atoms form a molecule of hydrogen gas and tiny gas bubbles form in the plate. This process will go on and on with an electric current continuously traveling the circuit until all the zinc in the negative plate is used up. When it is used up, of course there will be no more electrons to be released from the zinc, disabling the flow of the electrons in the circuit (Battery, electric, 1983).