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Old Mar 29th 2014, 10:19 AM   #1
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Question Why units of enthalpy of fusion might matter in statistical modelling

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I would like to know in which units enthalpy of fusion (Hf) should be expressed in statistical models (i.e. MLR) and why ? Should it be expressed in J/g or kJ/mol ? I will be very grateful for an easy to understand expatiation for non physicist.
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Old Mar 31st 2014, 05:16 AM   #2
MBW
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There are generally three reasons for choosing the units for a quantity,
1) convention/tradition,
2) emphasis of a particular relationship,
3) sensible size of the result.

I don't know what the convention is for the Enthalpy of Fusion,
the sensible size is readily accomodated via standard prefixes.
so I will concentrate on reason 2.

A Mole is a large number (also known as Avagadros constant)
So the use of Mol indicates the energy per number of atoms (or Molecules).
The use of gram indicates the energy per unit of mass.

The relationship between Mole and gram depends on the material under consideration.

For example 1 mole of Hydrogen molecules (2 moles of Hydrogen atoms) has a mass of 2 grams
(OK not exactly, but pretty close)
1 mole of Helium atoms also has a mass of 4 grams,
1 mole of Carbon12 atoms has a mass of 12 grams, etc...

Last edited by MBW; Mar 31st 2014 at 05:29 AM. Reason: mistake
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energy and work, enthalpy, fusion, matter, modelling, statistical, statistical physics, statistics help, thermodynamics, units



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