How is equilibrium constant of a reaction related to the temperature of

reaction?

And recall that the free energy change upon reaction is related to both the enthalpy and entropy changes

Although the free energy change is strongly dependent on temperature, usually the enthalpy and entropy changes upon reaction are NOT temperature dependent (or at least not very much so). This implies that the free energy is a linear function of temperature. Combining the above two equations:

substituting in the equilibrium constant

and finally

Remember that the enthalpy and entropy changes are regarded as constants with respect to temperature, so the equilibrium constant is exponentially dependent on temperature. The relative change in equilibrium constant as a function of temperature is usually not expressed as above but as the van''t Hoff equation