PHYSICAL CHEMISTRY IN BRIEF

CHAP. 11: ELECTROCHEMISTRY [CONTENTS] 379

where we assume, in compliance with the Debye-H ̈uckel limiting relation, thatγH+=γHA−=γ±
andγA^2 −=γ±^4.
If we do not consider any other ions in the solution but those formed in consequence of
reactions (11.62) and (11.63), we may rewrite equation (11.64) to

K=

c α(1 +α)γ±^4

1 −α

1

cst

, (11.65)

wherecis the initial concentration of the acid andαis the degree of dissociation of the anion
HA−.
A strong diacidic base B(OH) 2 dissociates in the second stage completely and in the second
stage up to the attainment of equilibrium:

K=

cB2+cOH−γ±^4

cBOH+

1

cst

, (11.66)

Equation (11.65) also applies here, withcstanding for the initial concentration of the base and
αfor the degree of dissociation of the cation BOH+.
We do not present relations describing the dissociation of strong tribasic and higher acids or
triacidic and higher bases. We would obtain them in a similar way—it would be enough to write
equations for the dissociation in higher stages and the corresponding equilibrium constants.

11.5.7 Hydrolysis of salts

Hydrolysis is a phenomenon that occurs in the salts of strong bases and weak acids (e.g. sodium
acetate), in the salts of weak bases and strong acids (e.g. ammonium chloride), and in the salts
of weak bases and weak acids (e.g. ammonium acetate). These salts are strong electrolytes and
consequently they dissociate in aqueous solutions completely. The dissociation products, i.e.
the anion of a weak acid A−or the cation of a weak base B+, react further with water until a
hydrolytic equilibriumis established.

11.5.8 Hydrolysis of the salt of a weak acid and a strong base

If we denote the salt of a strong base and a weak acid using the symbol NaA, the reactions
taking place can be written as
NaA −→Na++ A− (11.67)