Error in the solutions manual for 16.109

[Zellmer, Robert]

EOC exercise 16.109 asks you to order some 0.10 M salts in order of increasing acidity,
from least to most acidic.  The order is correct in the solutions manual.  However, the
way they used the greater than/less than sign is confusing.  The order with a better
use of the < > sign is

CH3CO2Na < NaF < CH3CO2NH4 = NaNO3 < NH4NO3

They used ">", which doesn't really make sense with the question which was asked,
putting them in order of increasing acidity.

Normally, if we asked you to list 3 acids, HA, HB and HC, in order of increasing acid
strength (or acidity of the soln if each has the same conc.) we would show the
answer as HB < HA < HC (assuming HC was the strongest and HB the weakest).

By the way, the way they've indicated the ammonium salts is a little strange.
For the formulas for salts (ionic cmpds) the cation comes first in the formula
(and the name).  So, for sodium acetate the correct formula (the one you would
see most often) is NaCH3CO2.  The same for ammonium acetate, NH4CH3CO2.
They're writing them more like an organic chemist or biochemist might write them,
with the positive ion next to the negatively charged oxygen atom of the carboxylate
group,  CH3CO2^- NH4^+, and then get rid of the charges to get CH3CO2NH4.

For the CH3CO2NH4 you get CH3CO2^- and NH4^+.  You need to look at the
Kb for the thing that's acting as the base, CH3CO2^-, and compare it to the Ka
for the thing that's acting as the acid, NH4^+.  If Ka > Kb the solution will be
acidic, if Ka < Kb the solution will basic, and if Ka = Kb the soln will be neutral.

Dr. Zellmer
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