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Define the following. (a) Molar Heat of fusion (b) Molar Heat of vapourisation (c) Molar Heat of sublimation (d) Heat of Transition |
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Answer» Solution :a. Molar Heat of fusion: The molar heat of fusion is defined as " The change in ENTHALPY when one mole of a solid substance is converted into the liquid state at is melting POINT". For example heat of fusion of icecan be represented as `H_(2)O_((s))overset(273K)rarrH_(2)O_((l))DeltaH_("fusion")=+5.98KJ` b. Molar Heat of vapourisation : The molarheat of vapourisation is the define as "The change in enthalpy when one mole of liquid is converted into vapour or gaseous state at its BOILING point " For example , heat of vapourisation of water can be represented as. `H_(2)O_((l))overset(373K)rarrH_(2)O_((g))DeltaH_("vap")=+40.626KJ` c. Molar Heat of sublimation: Molar Heat of sublimation is defined as "The change in enthalpy when one mole of a solid is directly converted into the gaseous state at its sublimation temperature ". For example , the heat fo sublimation of iodine is represented as `I_(2_((s))) rarrI_(2_((g))) DeltaH_("sub")=+62.42KJ` Heat of Transaction : The Heat of transaction is defined as " The change in enthalpy when one mole of an element change Fromone ALLOTROPIC form to another. For example , the transaction of DIAMOND into graphite may be represented as `C_(("diamond"))rarrC_(("graphite"))DeltaH_("trans")=+13.81KJ` `S_(("monoclinic"))rarrS_(("rhombic "))DeltaH_("trans")=-0.067KJ` |
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