Synthetic Inorganic Chemistry

IONIC REACTIONS 101

BASES

Substance

KOH, NaOH

Ba(OH) 2 <=> Ba++ + 2OH~

NH4OH

Percentage ionization in

0.1 equivalent solution

86

75

1.4

Ca(OH) 2 , Mg(OH) 2 are but slightly soluble, but so far as they do

dissolve they are dissociated to about the same extent as Ba(OH) 2

in a solution of the same concentration.

The hydroxides of the heavy metals are very insoluble and, as a

rule, very weakly basic.

AgOH is soluble to the extent of 1 part in 15,000 of water, in

which solution about 33 per cent of its molecules are ionized. It is

thus a moderately strong base.

Hydroxides of the type Zn(0H) 2 , Fe(OH) 2 , Mn(0H) 2 are less

basic than AgOH, and hydroxides of the type Fe(OH) 3 , Cr(OH) 3 ,

A1(OH) 3 are still much less basic.

Pure water contains 0.000,000,1 mole of H+ ions and 0.000,000,1

mole of OH~ ions per liter.

that given in the table, for example hydrochloric acid in 12 N so-
lution is only 13 per cent ionized.
The data above have been calculated from measurements of
electrical conductivity and freezing-point lowering. Although
both methods give concordant results for the degree of ionization,
it has for a long time been felt that these results are subject to
considerable uncertainty. The proximity of other ions retards or
dampens the effect of ions in causing electrical conductivity or
lowering of freezing point in such a way that the calculated per-
centage of ionization is almost certainly too low for strong electro-
lytes. For weak electrolytes the data in the above table are
reliable. The practice generally followed in the succeeding pages
of ignoring any un-ionized fraction of salts, strong acids, and
strong bases has a good deal of justification beyond that of mere
convenience.
IONIC REACTIONS
It is very probably true that all chemical reactions are due to a
rearrangement of the electrical forces residing in the atoms and
molecules concerned. Reactions taking place in water solution