Question

1. Define standard heat of fusion (∆H°_fus ) and standard heat of vaporization (∆H°_vap ). Explain why the standard heat of fusion (∆H°_fus ) is less than the standard heat of vaporization (∆H°_vap ) for most substances

Answer 1

standard heat of fusion (∆H°_fus ) = The amount of heat absorbed when one mole of a solid substance converts into liquid at its melting point.

  standard heat of vaporization (∆H°_vap )   = The amount of heat absorbed when one mole of a liquid substance converts into vapor at its boiling point.

for most of the substances, ∆H°_vap   >    ∆H°_fus  

because generally Boilingpoint of the substance greatertha its meltingpoint.