The specific latent heat of vaporization of a pure substance is substantially greater than its specific latent heat of fusion because vaporizing requires completely separating the molecules against intermolecular forces and performing work against external pressure, whereas melting requires only overcoming the long-range order of the crystalline lattice.
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True. The specific latent heat of vaporization is substantially larger than the specific latent heat of fusion because vaporization requires completely overcoming intermolecular cohesive forces to transition molecules into the gas phase, in addition to performing work against atmospheric pressure during expansion, whereas melting only disrupts long-range lattice order while keeping molecular spacing nearly identical.
The statement is true because vaporization involves breaking all intermolecular bonds to create a gas phase and doing external work against atmospheric pressure during large volume expansion, whereas fusion only weakens lattice alignment without significant separation or expansion.
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Microscopic and Thermodynamic Basis of Latent Heat of Fusion vs. Vaporization