Question

Assume that three equilibrium solutions were placed in a water bath, and allowed to re-equilibrate at the higher temperature. As a consequence of heating, the absorbance of the solution was found to decrease. Explain this observation and predict what will happen to the Kc value for the rxn and if the fwd rxn would be endothermic or exothermic.

Answer 1

If the farword reaction would be endothermic, Kc value will increase and if it is exothernic Kc will decrease.

Because, it is given that on heating the absorbance of solution was decreased. Which means the concentration of solutions was decreased. decrease in Conentration is the consequnece of increase in volume on heating.

Endothermic reactions require energy, hence favours farword on heating and thus increase in KC.

Exothermic reactions release energy, hence favours backward on heating and thus decrease in Kc.