Effect of Ionic Size on Equilibrium Constant of Some Uni-Bivalent Ion Exchange reactions

Abstract

Ion exchange resins in chloride and iodide form were equilibriated
with oxalate ion solution of seven different concentrations
from 0.010 M to 0.050 M, in temperature range of 30 to 45°C. The
difference in the ionic size of exchangeable CI^- and I^- ions on the
resin results in variation of equilibrium constant (K) values, i.e., for
Cl^-/C₂O₄^2-   exchange value of K at 30°C was calculated to be 19.5,
while for I^-/C₂O₄^2-  exchange the value of K was calculated to be
0.260 for same temperature. For both uni-bivalent exchanges the
equilibrium constant (K) values increases with increase in temperature,
indicating the endothermic ion exchange reaction having enthalpy of
12.2 kJ/mole for Cl^-/C₂O₄^2-  exchange and 14.5 kJ/mole
for I^-/C₂O₄^2- exchange.