response of equilibria to pressure as relating to moles

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Sol Lee 2H
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Joined: Fri Sep 25, 2015 3:00 am

response of equilibria to pressure as relating to moles

Postby Sol Lee 2H » Sun Nov 22, 2015 10:53 pm

Conceptually, how does it work that having more moles of reactants or products affect the direction of reaction when pressure is increased or decreased? I know that when volume decreases and more moles of gas is on the reactant side, then the reaction proceeds to the right, and vice versa, but what is happening here?

Ashlee Joan Macalino 3J
Posts: 36
Joined: Fri Sep 25, 2015 3:00 am

Re: response of equilibria to pressure as relating to moles

Postby Ashlee Joan Macalino 3J » Sun Nov 22, 2015 11:16 pm

When the volume in a reaction is increased, the inverse will occur such that the pressure will be reduced. According to Le Chatelier's principles, this will cause a shift to the right since the increased volume will want to produce more moles of gas. However, in order to restore the reaction to equilibrium, the reaction will therefore shift to the left in order to counteract changes to equilibrium. On the flip side, when you reduce the volume of a mixture, a shift will occur in the direction that creates fewer moles of gases. When you increase the volume of a mixture, a shift will occur in the direction that creates more moles of gases. Because the amount and concentration of moles are directly related to both pressure and volume, you can use gas laws and the relationship of moles (g), pressure, and volume to calculate shifts in equilibrium using Le Chatelier's.

Kanwaldeep Rai 2H
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

Re: response of equilibria to pressure as relating to moles

Postby Kanwaldeep Rai 2H » Sun Nov 22, 2015 11:22 pm

For this problem, think about it terms of a system as a whole. So, when you increase the pressure or decrease the volume, the molecules are hitting the walls faster causing stress on the system- an increase in the total pressure of the system. In order to reduce the stress on the system, the reaction tries to create a way reduce the number of particles of gas. So, the reaction ends up favoring the side with least number of moles.

Hopefully this helped.


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