Synthetic Inorganic Chemistry

NEUTRALIZATION^109

products of neutralization are always un-ionized water and a salt.
But the table of ionization values tells us that all salts are highly
ionized, although acids and bases may or may not be.
Neutralization of a Strong Add and a Strong Base. When a
strong, that is, a highly ionized acid (for example, HC1), is neutral-
ized with a strong base (for example, NaOH), and the resulting
salt, in this case NaCl, is soluble, the essential reaction is the for-
mation of water from its ions.
H+
OH~
1
H 2 O

cr

Na+

In this connection a most interesting fact comes to our attention,
namely, that the heat produced by the neutralization of one
equivalent of any strong base with one equivalent of any strong
acid is always the same, namely, 13,700 calories. That the heat
effect is the same is in itself a strong indication that the reaction
is in each case the same, and this fact, then, is in entire accord with
our conception of the reaction of neutralization. In the follow-
ing table are given some of the measured values of the heat of
neutralization of acids and bases, both weak and strong.
Heat evolved by the neutralization of one equivalent of
acid with one equivalent of base (in calories)

HC1

NaOH 13,700

KOH 13,700

NH4OH 12,400

HNO 3

13,700

13,800

12,500

HC 2 H 3 O 2

13,300

13,300

12,000

H 2 S

3,800

3,800

3,100

Neutralization of a Weak Add or a Weak Base. Weak acids
and weak bases are but sparingly ionized. Acetic acid is typical
of a rather weak acid, being 1.4 per cent ionized in 0.1 N solution.
Ammonium hydroxide is typical of a rather weak base, it having
the same degree of ionization as acetic acid, namely, 1.4 per
cent in a 0.1 N solution. Neither acetic acid nor ammonium
hydroxide solution conducts the current strongly, but if the two
solutions are mixed, we observe what is a rather startling fact if
we have not thought out in advance what to expect, namely,
that the resulting solution is a strong conductor.