Define 'entropy of fusion' and 'entropy of vapourisation and write expressions to represent them.

Explanation

Entropy of fusion: it is defined as change in entropy when one mole of a solid substance transforms into the liquid form at its melting point. It is represented by `Delta_("fus")S`. It is given by,
`Delta_("fus") S= S_("liquid")- S_("solid")= (Delta_("fus")H)/(T_(m))`
Where, `Delta_("fus")` H is the enthalpy of fusion per mole and `T_(m)` is the melting temperature of solid in kelvin. Entropy of vaporisation: It is defined as change in entropy when one mole of a liquid changes into vapour form at its boiling point. It is represented by `Delta_("vap")S`. It is given by,
`Delta_("vap")S= S_("vap")- S_("liquid")= (Delta_("vap")H)/(T_(b))`
Where, `Delta_("vap)H` is the enthalpy of vaporisation per mole and `T_(b)` is the boiling point of a liquid in Kelvin.