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Direction of equilibrium if you remove heat from exothermic reaction

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  1. Apr 22, 2015 #1
    If you remove heat from an exothermic reaction will the equilibrium shift to the products or to the reactants according to le chatelier's principle
     
  2. jcsd
  3. Apr 22, 2015 #2

    Borek

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    Can you state Le Chatelier's principle?
     
  4. Apr 22, 2015 #3
    With my own words I can state it as a law that predicts the direction of an equilibrium change(to the left means reactants, to the right means products) caused by changes such as pressure, changes, or amount of reactants/products added to the system.

    From wiki here is the law "Le Châtelier's principle, also called Chatelier's principle or "The Equilibrium Law", can be used to predict the effect of a change in conditions on a chemical equilibrium"
     
  5. Apr 22, 2015 #4

    Borek

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    So you have stated what it is, I asked what it says.
     
  6. Apr 22, 2015 #5
    It says that you can predict the direction of equilibrium due to a change in the system, equilibrium will always want to level out or be balanced. For example if you remove some products from a reaction then the products will be producing less reactants and the equilibrium will shift to the right(product side). My source of information did not go into detail about explaining what it says.
     
  7. Apr 22, 2015 #6

    Borek

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    What is you treat heat as a product?
     
  8. Apr 23, 2015 #7

    DrDu

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    What do you mean with "removing heat"?
    Your question is very vague.
    Consider the following example: Freezing of water is an exothermic reaction. At 0 degrees C water and ice are in equilibrium. You can remove heat from the system and more product (ice) will form. However, the equilibrium constant will not change as the concentrations of reactants and products don't change. There is always pure water and pure ice.
     
    Last edited: Apr 23, 2015
  9. Apr 23, 2015 #8
  10. Apr 23, 2015 #9

    DrDu

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    Yes, but he wasn't asking about the effect of changing the temperature, was he?
     
  11. Apr 23, 2015 #10
    This is similar to a question I have on homework I did not want to say the exact question but if it helps I will becuase I am not sure if my inference is correct.. Here is the actual question

    "
    Consider the following reaction occurring in a closed chemical system. Assume that this reaction is at equilibrium and that in general the reaction to the right is favored.

    CH3CH2OH + 3O2 ---><--- 2CO2 + 3H2O ∆H = –1,235 kJ/mol
    If heat is removed from the system, how will the reactions shift to reach equilibrium?"

    I believe the equilibrium would shift to the right because if you treat matter as energy and energy is released by the products then removing heat is like removing matter from the products causing the equilibrium to shift to the right. Am I correct?
     
  12. Apr 23, 2015 #11

    DrDu

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    Poor lad! Who asks such nonsensical questions and what are you supposed to learn from them? Burning ethanole as an example of a reaction reaching equilibrium!?!
     
  13. Apr 23, 2015 #12
    ok?
     
  14. Apr 23, 2015 #13

    DrDu

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    Ok, so leaving aside the strangeness of the system chosen, there are two different ways to suck heat from this system: either you cool it (at constant pressure) or you compress it (at constant temperature). In the first case your argument is correct. However in the second case, the equilibrium shifts to the left.
     
  15. Apr 24, 2015 #14
    The correct answer is the equilibrium would shift to the right. I am not sure if I was thinking correctly to get the solution but it is correct. Thanks for the help friends.
     
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