Editing Chemical equilibrium (section)

==Effect of temperature==

The effect of changing temperature on an equilibrium constant is given by the [[van 't Hoff equation]]
:<math>\frac {d\ln K} {dT} = \frac{\Delta H_\mathrm{m}^\ominus} {RT^2}</math>
Thus, for [[ENDOTHERMIC]] reactions (Δ''H'' is negative), ''K'' decreases with an increase in temperature, but, for [[EXOTHERMIC]] reactions, (ΔH is positive) ''K'' increases with an increase temperature. An alternative formulation is
:<math>\frac {d\ln K} {d(T^{-1})} = -\frac{\Delta H_\mathrm{m}^\ominus} {R}</math>
At first sight this appears to offer a means of obtaining the standard molar enthalpy of the reaction by studying the variation of ''K'' with temperature. In practice, however, the method is unreliable because error propagation almost always gives very large errors on the values calculated in this way.