Temperature and Equilibrium

[EriMizuguchi2K]

Hi,

I was a little confused about what happens to the K of a reaction when the temperature is changed? I know it has something to do with whether the reaction is endothermic or exothermic, but could someone explain this concept to me? Thank you!

[Cassidy Chiong 2J]

Say we're given a reaction A+B <--> C, and this reaction is exothermic in the forward direction and endothermic in the reverse direction. We could then rewrite this reaction as A+B <--> C + Heat. If we increase the temperature of this reaction, then we would be adding "product", causing the the reaction to shift left and form more reactant. Using the equation K=[P]/[R], an increase in reactant would result in a lower K value. Conversely, if we decrease the temperature of the reaction, then we would be removing "product," causing the reaction to shift right and form more product. An increase in product would result in a higher K value.

[Marilyn]

The equilibrium constant decreases when the temperature increases in exothermic reactions.

In endothermic reactions, K increases with temperature.

[Hudson2J]

Depending on if the reaction is endothermic or exothermic, we can treat heat as a product or reactant. The reaction shifts away from whichever side heat is on (for example it would be a product in an exothermic reaction) if the temperature is raised. This shift in equilibrium causes a change in the equilibrium constant.