Question

With reference to the nature of electrodes, which one is an inert electrode?
A. Silver
B. Copper
C. Graphite
D. Nickel

Answer 1

Hint:Let us first understand the basic definition of an electrode, nature of electrodes and the term “inert”.
 An electrode is an electrical conductor by which electrons flow through to generate current. There are two types of electrodes- cathodes and anodes. Cathode attracts the positively charged cations. Anode attracts negatively charged anions.

Complete answer:
To understand the nature of electrodes, let us take the example of a copper electrode where our main objective is to purify copper. We construct the anode, i.e. the positive electrode with impure copper and the cathode, i.e. the negative electrode with pure copper. During electrolysis (flow of electrons when electricity is passed), the anode loses its mass as copper dissolves and the cathode gains mass as copper is deposited. Oxidation takes place at the anode by loss of electrons whereas the reduction takes place at the cathode by the gain of electrons.
We have to remember that the term “inert” generally means non-reactive. With respect to chemical reactions, inert means having little or no ability to react. Inert electrodes, on the other hand, are electrodes which allow the flow of electrons without actually taking part in the electrolysis chemically.
In reference to the choices given, silver, copper and nickel are chemically reactive with greater potential to chemically dissolve during electrolysis. Therefore, the option A, B and D are incorrect.
We have to remember that an electrode made of a substance such as carbon does not take part in the electrolysis reaction, they act as the site of electron exchange only. Graphite, a crystalline form of carbon is chemically inert. We have to remember that the carbon is an inert substance which is insoluble in water, diluted acids and bases, as well as organic solvents.
Thus, it can be concluded that with reference to the nature of electrodes, Graphite is an inert electrode. Therefore, the correct option to the question above is option C.

Note: In order to solve problems which include electrodes for electrolysis, the basic understanding of what constitutes the electrodes is important. Graphite is the unique electrode material which fulfils the following criteria:
-Thermal and electrical conductivity
-Machinability
-Thermal expansion and mechanical strength.