Authors : A. P. GANORKAR1 and D. M. CHAFLE2
Page Nos : 383-388
Description :
The equilibrium constant in the standard state Kstd for the uni-bivalent ion exchange
between the resin (R) and the aqueous solution (aq)
2X -
(R) + Y 2 -
(aq) 2X -
(aq) + Y 2 -
(R) ,
where X- = Cl- and Y2- = C2O4
2-, have been determined in anion exchange resin Thermax
A27 with due regards to mean activity coefficients of ions both in the solution and in
the resin. For this purpose the apparent equilibrium constants, Kapp, for various
equilibrium concentrations of the bivalent ion, C2O4
2-, in the solution have been
calculated from the expression.
[CY
2-
(R)] [CX-(aq) (aq)]2
[CX
-
(R)]2 [CY
2-
(aq) (aq)]
where the ‘C’s are the concentrations of the ions and (aq) is the mean activity coefficient
of the ions in the solution. From this, the equilibrium constant in the standard state,
Kstd, is determined by a graphical method. The resin in its purely univalent anion form
is chosen as the standard state. From Kstd, for various temperature the enthalpy
change for the ion exchange reaction has been evaluated.
