In the einstein model, a solid containing n atoms is represented by a set of 3n identical but distinguishable harmonic oscillators of frequency v. the chemical bonding between the atoms lowers the free energy by en. assume that v and ε are independent of the volume. present a complete derivation of the chemical potential of atoms in this solid.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.