effect on equilibrium by changing volume

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effect on equilibrium by changing volume

Postby 505166714 » Mon Jan 14, 2019 6:59 pm

How do I explain the change in equilibrium with reaction quotient (Q) after changing the volume?

Jake Gordon 1A
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Re: effect on equilibrium by changing volume

Postby Jake Gordon 1A » Mon Jan 14, 2019 7:55 pm

Well, it depends how the volume has been changed. Lets say that the volume is halved, this doubles pressure because they are inversely related.
for N2+ 3H2 ==> 2NH3
If the partial pressures at equilibrium are all .1, the K value is 100

When the volume halves, the concentration doubles because C=number of moles divided by volume. if n is constant and V decreases, C increases. The new concentrations are now .2, now we would be calculating Q because it is not at equilibrium
Q would equal 25 which is less than K meaning that the forward reaction is favored (there are currently many reactants)

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Re: effect on equilibrium by changing volume

Postby JacobHershenhouse3G » Mon Jan 14, 2019 8:02 pm

Remember that Q is the constant at any given point in time and has applications that dont involve the changing of equilibrium concentrations. The important thing to note is that BOTH K and Q change when you alter volume or temperature (to reflect the change in equilibrium concentration values). So, if you want to express that equilibrium has changed, demonstrate that there is a new K, not a new Q. Hope this helps!

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