Graphite is more stable than diamond and fullerene because its enthalpy of formation ΔHof is less than that of both diamond (1.98 kJ mol-1 ) and fullerene (38.1 kJ mol-1 ) at room temperature and atmospheric pressure.
Why graphite is the most stable allotrope of carbon?
In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. … Graphite is the most stable allotrope of carbon.
Why is diamond not thermodynamically unstable?
Diamond is thermodynamically unstable because delta G for diamond to graphite is negative and therefore spontaneous, but the transition from diamond to graphite has a large activation energy barrier, so diamond is not likely to transition on its own to graphite and is therefore kinetically stable.
Which is more stable between diamond or graphite?
Even with accounting for the flexural modes, graphite is still more stable than diamond at 0 K, but the difference in Gibbs energies is even smaller (1.39–1.55 kJ mol−1) than at room temperature.
Why diamond is more stable than graphite at high pressure?
In diamond, each carbon is bonded to 4 others, in the rigid adamantane structure. … At normal temperatures and pressures, graphite is only a few eV more stable than diamond, and the fact that diamond exists at all is due to the very large activation barrier for conversion between the two.
Why graphite is thermodynamically more stable?
Graphite containes one delocalised electron per carbon. These cause greater attraction between carbon atoms hence giving stronger bonds, more stability to the structure.
Is graphite less stable than diamond?
Although graphite is a more stable form of crystalline carbon than diamond under normal conditions, there is a significant kinetic energy barrier that the atoms must overcome in order to reach the lower energy state. Diamond is therefore a metastable state.
Why is diamond different from graphite?
Both have Giant Covalent Structures, resulting in very high melting temperatures. However each carbon atom in Diamond has 4 covalent bonds with other Carbons, making it extremely strong and hard. On the other hand, each carbon in graphite is bonded to three carbons, and therefore graphite is formed in layers.
Is graphite to diamond endothermic?
The conversion of diamond into graphite is an endothermic reaction.
Does diamond turn into graphite?
Diamond is the high-pressure phase that forms deep in the earth. Under normal conditions, diamond is metastable, meaning that it converts back to graphite when the process is initiated with sufficient energy. … It can switch its internal structure to a different order, thereby turning into graphite.
What is the meaning of thermodynamically most stable?
Thermodynamic stability occurs when a system is in its lowest energy state, or in chemical equilibrium with its environment. … State A is said to be more thermodynamically stable than state B if the Gibbs free energy of the change from A to B is positive.
Which has more thermal conductivity graphite or diamond?
Diamond is better thermal conductor than graphite. Electrical conductivity is due to availability of free electrons, thermal conduction is due to transfer of thermal vibrational energy from one atom to another atom. A compact and precisely aligned crystals like diamond thus facilitate better movement of heat.
How can diamond be more stable than graphite under any circumstances since it clearly has less entropy than graphite?
A given quantity of graphite always has more entropy than the same quantity of diamond at the same temperature and pressure. Diamond can still be more stable than graphite under high pressure. This is because the total entropy of the system with the environment tends to increase.