describe the construction, working and usefulness of a dry cell ,with the help of diagram.
Answers
A dry cell consists of a zinc container and its base works as the negative electrode. A carbon rod is placed at the centre with a brass cap which acts as the positive electrode.
This is surrounded by a mixture of manganese dioxide and charcoal in a muslin bag. The electrolyte uses is a moist paste of ammonium chloride. The outer body of the zinc container is insulated with cardboard.
When the dry cell is connected in a circuit comprising a bulb, current flows in the circuit due to the chemical reaction that takes place in the cell. This makes the bulb glow. The dry cell is a primary cell and it cannot be recharged.
Dry cell is a modified Leclanche’s cell in which the electrolyte is present in the form of gel or powder so that it doesn’t spill and hence can be portable and compact in size. The cells we use in daily life in torch lights, wall clocks are generally dry cells.
Dry cell is a primary electric cell that uses zinc container as cathode, carbon rod as anode and ammonium chloride or zinc chloride as electrolyte and manganese dioxide as depolarizer.
An electric cell is a device that converts chemical energy to electrical energy. A simple electric cell is made up of an electrolyte and two electrodes. The electrolyte is a conductive solution containing anions (negatively charged ions) which moves towards the anode (negative electrode)and cations (positively charged ions) moves towards the cathode (positive electrode). So, we have an excess of electrons in the anode (which is the negative terminal of the cell) and a deficiency of electrons in the cathode (which is the positive terminal of the cell).
*Zinc is a medium reactive metal and is oxidized slowly by air.It is electro positive as compared to carbon which is used as positive electrode in dry cell.So, it donates electrons and a current is produced. It is not very reactive and is consumed slowly, so it is used in dry cells.