mistake in solutions manual for 16.46(a)

[Zellmer, Robert]

There is a mistake in the solutions manual's answer to 16.46(a).

The question is a T/F question, "All strong bases are salts of the hydroxide ion".
The answer in the solutions manual is True.  That is not correct.

As stated in Section 16.5 on strong bases, the most common strong bases are the hydroxides
of group 1A metals and the heavier group 2A metals, Ca(OH)2, Sr(OH)2 and Ba(OH)2.
Mg(OH)2 is considered a "strong base" (strong electrolyte) since whatever part of it which
dissolves, dissociates completely.  However, since it's not very soluble (and we'll see later
the Mg^2+ ion is slightly acidic) it's not usually included with the other group 2A bases.

It then goes on to say at the end of that section strongly basic solutions are also created by
certain substances which react with water to form OH- and gives the example of O^2-,
the oxide ion.  This is the conjugate base of OH-, if OH- acted as an acid, which it doesn't,
it's the strongest base that can exist in water.  Thus, the conjugate base of OH-, assuming it
acted as an acid, O^2-, is a stronger base than OH-.

There were several others I mentioned in class.  It's also discussed in the following two
links at the "Helpful Tidbits" link.  I also list some other examples of unusual strong bases
in the first link.

Some Aspects about Acids and Bases<https://cbc-wb01x.chemistry.ohio-state.edu/%7Erzellmer/chem1220/faq/acid_base.txt>

Further Discussion on Acids and Bases<https://cbc-wb01x.chemistry.ohio-state.edu/%7Erzellmer/chem1220/faq/amphoterism.txt>


Dr. Zellmer
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