Question

Write the name of the cell which is generally used in transistors. Write the reactions taking place at the anode and the cathode of this cell.

Answer 1

Hint: The cell that is commonly used in transistors is a type of primary battery as it cannot be reused. It has zinc as its anode and carbon as cathode.

Complete answer
It is known to us that an electrochemical cell has two chambers which are divided by a salt bridge. Inside the cell, the electron flow occurs from anode (where oxidation process occurs) to cathode (where reduction process occurs).
We might not see transistors being used as widely in present times as they were famous years ago but the cell that is commonly used in transistors still finds its uses in many devices such as clocks. This cell is known as a dry cell or Leclanche cell. It is made of a zinc container that acts as its anode and there is a rod of graphite in the centre that is used as its cathode. We know that in these cells, chemical energy is converted into electrical energy. So, like any other galvanic cell, oxidation will take place at the anode and there will be reduction at the cathode.
Now, in this cell, the space between the two electrodes, zinc and carbon, is filled with manganese dioxide, black carbon as well as a moist paste of ammonium chloride and zinc chloride. These provide the ions and mediums for the flow of electrons in the cell. Now, we can write the oxidation reaction that is taking place at the zinc anode as follows:
\[{\rm{Zn}} \to {\rm{Z}}{{\rm{n}}^{2 + }} + 2{e^ - }\]
At the graphite cathode, reduction reaction can be written as:
\[{\rm{Mn}}{{\rm{O}}_2} + {\rm{NH}}_4^ + + {e^ - } \to {\rm{MnO}}\left( {{\rm{OH}}} \right) + {\rm{N}}{{\rm{H}}_{\rm{3}}}\]

Note:
In this cell, zinc is getting oxidized from zero to $ + 2$oxidation state and manganese is getting reduced from $ + 4$ to $ + 3$ oxidation state.