EXPERIMENTS 255solution the following distinct stages in the process were noted:
(a) The gas passed into the solution in distinct bubbles and was
in large part absorbed. (6) Effervescence took place with minute
bubbles arising from every part of the solution, (c) Effervescence
ceased, and the gas entered the solution again in clear, distinct
bubbles, but still it was for the most part absorbed, (d) The gas
passed through the solution in distinct bubbles and was entirely
unabsorbed. Look up the degree of ionization of both hydrogens,
both of sulphurous and carbonic acids. Write equations for the
reactions taking place during each of the stages enumerated
above.
Experiments
The behavior of the halogens with aqueous solutions of bases,
in fact even with seemingly dry bases such as calcium hydroxide
in which a trace of moisture is present, can best be accounted for
when it is taken into account that they hydrolyze extensively.
Thus in chlorine water, that is, water nearly saturated with chlorine
at atmospheric pressure, chlorine comes to equilibrium with its
hydrolysis products HC1 and H0C1 with about two-thirds of the
chlorine present as Cl 2 and one-third in the form of equimolal
amounts of HC1 and H0C1.
Cl 2 + H 2 O ^ HC1 + H0C1A similar condition exists in water solutions of bromine and
iodine except that iodine is much less soluble than either chlorine
or bromine.
- Hypochlorites. (a) To 10 cc. of freshly prepared
chlorine water, which has a distinct yellow color, add 6N
NaOH until the yellow color has disappeared. Close the test
tube and shake thoroughly, and then note that the odor of
chlorine has also disappeared.
Since two-thirds of the chlorine in chlorine water is in the form
of Cl 2 , the yellow color is apparent in spite of the fact that one-
third of the total chlorine exists in the form of the colorless com-
pounds HC1 and HOC1. Addition of sufficient base neutralizes
both the acids, upsetting the equilibrium, and the hydrolysis
runs to completion. The salts NaCl and NaOCl are both color-
less.