Question

Thermodynamically most stable form of carbon is:
A. Graphite
B. diamond
C. lonsdaleite
D. chaoite

Answer 1

We know that under normal and standard conditions, all the carbon allotropes are solids. Thermodynamic stability is used to determine whether a given reaction or a substance could be spontaneous or not and to determine when a system is in its lowest energy state. Such reactions that do not require energy are called thermodynamically favored reactions.

Complete step by step answer:
Now, we will discuss all the above options to find out the most stable form of carbon.
We know that graphite is the crystalline form of pure carbon. At standard temperature and pressure, it is thermodynamically the most stable form of carbon. As it is chemically inert or resistant, it requires a high temperature for reacting with oxygen.
Then, we have a diamond which is in solid form and an allotrope of carbon in which the carbon atoms are arranged in a cubic crystal form. The basic element of carbon is arranged in a tetrahedral structure. Each atom in the structure is bonded with its nearest four neighbors. Also, it is highly rigid and incompressible in nature.
Ionsdaleite is an allotrope of carbon which is popularly known as hexagonal diamond. It has a hexagonal lattice that contains interlocking rings of six carbon atoms.
Also, chaoite is known as white carbon which also belongs to the hexagonal crystal family. Chaoite is harder than graphite and its structure is quite similar to the structure of carbyne due to its electron diffraction pattern.
Therefore, we can conclude that graphite is a thermodynamically the most stable form of carbon.

So, the correct answer is Option A.

Note: We need to know that graphite is extensively used in the electrical industry to manufacture carbon electrodes and brushes in a dry cell. It is also used in nuclear reactors as it absorbs neutrons. Both graphite and diamond have similar chemical properties but different physical properties. The electricity conducting property of graphite is due to the free electrons present in its structure. These arise because each carbon atom is bonded to 3 other carbon atoms.