Ch 13 links, mistake in figure 13.4, etc.

[robert zellmer]

A short note about the 12th edition.  In the 12th edition the 
delta(H)_solvation
is referred to as the delta(H)_mix .

There are a few useful links on the class web page (see "Notes" section)
dealing with things we've covered in sections 13.1-13.4.  One of them is
a new link discussing the energy diagrams we covered on Friday.

The following two links deal with the last two examples from class
concerning concentration conversion problems.  You don't have to
do them the way I did in class but I've found it tends to make them
easier (simply because you can use one approach to do all of the
various conc. conversion problems).

  * *Chapter 13 - Conc. Conversion Ex 2 (Molarity --> molality)*
    <http://chemistry.osu.edu/%7Erzellmer/chem1220/notes/ch13_notes_conc_conv2.pdf>

  * *Chapter 13 - Conc. Conversion Ex 3 (mass % --> mole fraction &
    molarity)*
    <http://chemistry.osu.edu/%7Erzellmer/chem1220/notes/ch13_notes_conc_conv3.pdf>



The following two links deal with attractive forces, solubility effects 
and the solution
diagrams dealing with solution formation.

  * *Ch. 11, 12 & 13 - Review of IAF, Solids & Solubility*
    <http://chemistry.osu.edu/%7Erzellmer/chem1220/notes/ch11_12_13_rev.htm>

  * *Ch. 13 - Solution Formation and Solubility Effects*
    <http://chemistry.osu.edu/%7Erzellmer/chem1220/notes/ch13_soln_formation.pdf>



By the way, there is a mistake in Figure 13.4.  In the heading for the 
figure it has
delta(H)_solute + delta(H)_solute .  It should be delta(H)_solute + 
delta(H)_solvent .

Also, the "sizes" of the energies shown in the general diagrams in Fig 
13.4 and
the 3 main examples used in class are just examples.  The relative sizes of
delta(H)_solute , delta(H)_solvent , delta(H)_solvation will vary 
depending on the
type of solute and solvent (the attractive forces present between particles,
which can be ions, atoms or molecules).

When the solute is ionic, delta(H)_solute and delta(H)_solvation are 
very large
compared to delta(H)_solvent so delta(H)_solvent is essentially zero 
compared
to the other two (it can be ignored).

When I did the one for a gas dissolving in water I drew the diagram such 
that
delta(H)_solute is much smaller than those for the delta(H)_solvent and 
delta(H)_solvation .
For a gaseous solute delta(H)_solute is essentially zero because the gas 
molecules
are pretty much already separated (AF are ineffective in a gas). 
Hopefully this
makes sense.  The delta(H)_solvation is large because you form new 
(extra) AF
between the gas molecules and water molecules which didn't exist 
before.  This
produces energy (heat).  Think of it as the gas molecules going into the 
spaces
between the water molecules so the AF between the water molecules aren't
disturbed too much and now there's new AF between the gas molecules and
the water molecules.

AF = attractive forces
IAF = Intermolecular AF (those between molecules)


Dr. Zellmer
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