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physics, specific latent heat of Vap > spec LH of fusion??help

any1 noe why the specific latent heat of vaporisation is higher than specific latent heat of fusion for the same substance?

thankx!
:smile:
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ryan750
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any1 noe why the specific latent heat of vaporisation is higher than specific latent heat of fusion for the same substance?

thankx!
:smile:


All the energy supplied is used to break intermolecular bonds and change phase. The energy input becomes internal potential energy.
Perhaps think of the state model - with solids having closely packed molecules or atoms - liquids have less packed in molecules or atoms (except ice) and gases have much more free particles. From solid to liquid (fusion) the particles when supplied with energy will transmit this energy to surrounding molecules readily due to their close proximity to one another. This energy is then used to break the bonds ( or severely weaken them).
in the case of vaporisation where the liquids have weaker forces between each particle and where some may not be touching, the transmission of energy between particles is at a lower rate than in fusion. For vaporisation to occur the particles have to break the weak intermolecular forces and also to gain enough energy to escape from the liquid matrix of particles which requires kinetic energy. Perhaps it is this requirement for the particles to not only break their bonds but also to then gain kinetic energy through collisions with higher energy particles to then escape the liquid and become a gaseous particle. Just a theory - thanks for jogging my memopry of the subject anyway and getting me to look at my dusty physics book. :biggrin: :wink: :cool: :smile:

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