How does the equilibrium constant change with temperature?

1 Answer
Jan 11, 2014

For an exothermic reaction (#ΔH# is negative), #K# decreases with an increase in temperature.

For an endothermic reaction (#ΔH# is positive), #K# increases with an increase temperature.

You can calculate the effect of changing temperature on the equilibrium constant by using the van't Hoff equation

#(dlnK)/(dT) = (ΔH^°)/(RT^2)#, where #R# is the Ideal Gas Constant.

If you integrate this equation from #T_1# to #T_2#, you get

#ln((K_2)/(K_1)) = (ΔH^°)/R (1/(T_1) – 1/(T_2))#

Thus, if you know the #ΔH^°# and the equilibrium constant at one temperature, you can calculate the equilibrium constant at some other temperature.