During the teaching of physics and chemistry, students’ attention is mostly drawn to the work of batteries. They ask questions and want to have complete information about the structure and working principle of this current source. Since there is not enough information on batteries in textbooks, we would like to provide additional information on the structure and principle of operation of batteries.

A dry element, that is, a battery, the design of which is shown, is the primary source of electric current, and it is used in radio receivers and tape recorders, various clocks, microcalculators, flashlights, various toys, etc. Although the batteries are disposable, it should be noted that the use of this material is environmentally friendly.

The zinc tank that the batteries are made of serves as the anode. A carbon rod covered with a layer of manganese (IV) oxide and carbon acts as a cathode. A paste consisting of zinc chloride, ammonium chloride and water is used as an electrolyte.

The following half-reactions take place at the electrodes of the dry element:

At the anode: Zn (c) → Zn2+(water) +2e—

At the cathode: 2MnO2(c) + 2NH4+(aqueous) +2e—→ Mn2O3(c) + 2NH3(aqueous) +H2O(m)

The general equation for chemical reactions in batteries is as follows:

Zn (c) + 2MnO2(c) + 2NH4+(aqueous) → Zn2+(aqueous) + Mn2O3(c) + 2NH3(aqueous) +H2O(m)

The voltage of these batteries is usually from 1.25V to 1.50V.