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Le Chatelier's Principle

Posted: Wed Nov 29, 2017 8:57 am
Can someone explain how taking away heat affects the equilibrium reaction?

Re: Le Chatelier's Principle

Posted: Wed Nov 29, 2017 9:57 am
If the reaction is exothermic, taking away heat will make the reaction favor the products. If the reaction is endothermic, taking away heat will make the reaction favor reactants.

Re: Le Chatelier's Principle

Posted: Wed Nov 29, 2017 10:11 am
Exothermic means that the reaction will release heat as a product, therefore when you take heat away from this reaction, the reaction will continue to proceed towards the product to produce more heat to compensate for the fact that you've taken away heat from the products.

Endothermic means that the reaction requires heat as a reactant, therefore, when you take heat away from this reaction, the reaction will proceed away from the product and to the reactants because of the lack of heat.

If it helps, try thinking of heat as another "compound" in the products and reactants because it is a product or a reactant of an reaction depending on whether the reaction is endothermic or exothermic.

Re: Le Chatelier's Principle

Posted: Wed Nov 29, 2017 10:13 am
^To explain that a little bit, think of adding temperature to a system. Since the forward reaction is exothermic (favoring the products), that means that the system releases heat while forming the products. With the reverse reaction being endothermic, the system absorbs heat to form the reactants again. So if you add temperature to a system, the system has to do something with that heat. The only option is to absorb that heat, so the reactants would be favored. On the other hand, if you decrease the temperature, the system wants to release more heat to balance it back to equilibrium. Thus the products are favored and more heat is released.

Re: Le Chatelier's Principle

Posted: Wed Nov 29, 2017 1:41 pm
- If reaction requires heat (endothermic) while forming a product, then increasing the temperature will
favor products and equilibrium will be shifted to the right (K would increase).
- If reaction gives off heat (exothermic) while forming a product, then increasing the temperature will
favor reactants and equilibrium will be shifted to the left (K would decrease).
- If reaction requires heat (endothermic) while forming a product, then decreasing the temperature will
favor products and equilibrium will be shifted to the left (K would decrease).
- If reaction gives off heat (exothermic) while forming a product, then decreasing the temperature will
favor reactants and equilibrium will be shifted to the right (K would increase).