Chemistry - Le Chatelier's principle(help)
posted by Babelii .
Le Chatelier's principle states that " a dynamic equilibrium tends to respond as to relieve the effect of any change in the conditions that affect the equilibrium."
I understand the above, now i am trying to predict the response of the system and i am confused how to do it, so the below is my try to understand it, please help me and correct me and teach me how its done...
Co(h20)6,2+ +4cl- +50kJ (reversible) CoCl4,2- + 6h20
and we are adding distilled water
so the stress is the water molecules on the products side, so the products would be increasing, meaning the products sign has a increasing value, thus the reactants are decreasing and the reaction is favourable to the right side?
is that correct, i know i am confused please help me the prediction of system response.
No, it is not correct.
Let me restate Le Chatelier's Principle but in slightly different words. In a system in dynamic equilibrium the reaction will shift in the direction to undo what we've done to it.
So, yes, the water is on the product side, but starting here I do it differently than you did. Water has increased (and that's all you need to look at because that's the only change in the system; i.e., water has been added and that's the only stress at this point). So the system will try to undo what we've done; namely, the system will try to decrease the water. How can it do that? It can shift to the left because in doing so it uses water an that will decrease the H2O on the product side. Question answered. The reaction will shift to the left. Any time you ADD something (either concn increased or heat increased) the reaction shifts to the other side. So adding water makes it shift to the left, adding heat makes it shift to the right, adding Cl^- shifts it to the right, adding CoCl4^-2 shifts it to the left, etc. What do you do with DECREASING something. I'm lazy so I have just one case (the one I cited above) down pat. So when I see a question about decreasing something, I just ask myself which way it shifts from increasing the material, then move the opposite direction. :-)