Temperature and Keq

[663697]

For endo/exothermic reactions, why does a change in temperature affect the Keq of the reaction? The sources that I've found refer to heat as a reactant/product, and the reaction shifts accordingly when adding/removing heat from the system. But why does this shift also change Keq, if changes in concentration/pressure also cause shifts but maintain the same Keq?

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[JustinM88]

[^see thumbnail for best explanation I can think of right now...gets good after the "If we increase the Temperature" line; used an exothermic rxn as an example]
Maybe because "heat" isn't actually plugged into the Keq equation? Ie. it doesn't have a Molarity associated with it, so when we manipulate the heat variable, it causes the other variables to change and thus changes K?

 

[Doogie.Howser]

Temperature has an effect on the rate of the reaction as seen in the Arrhenius equation. Keq as you know is rate fwd/rate rvrs, and because temperature changes the rate, it changes the ratio of Keq.

 

[663697]

Temperature has an effect on the rate of the reaction as seen in the Arrhenius equation. Keq as you know is rate fwd/rate rvrs, and because temperature changes the rate, it changes the ratio of Keq.

Totally forgot about that! Now that I think about it, changing the concentration/pressure of the species wouldn't affect the rate constants, so the Keq remains constant in that case.