Changes in Pressure

Moderators: Chem_Mod, Chem_Admin

AKhanna_3H
Posts: 104
Joined: Wed Sep 18, 2019 12:19 am

Changes in Pressure

Postby AKhanna_3H » Thu Jan 23, 2020 9:22 pm

How does increasing the pressure affect the reaction? Are reactants or products favored?

Kristina Rizo 2K
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

Re: Changes in Pressure

Postby Kristina Rizo 2K » Thu Jan 23, 2020 9:47 pm

I know that the change in pressure doesn't effect the equilibrium constant. According to my lecture notes from week 1 Friday, Lavelle stated that when there is a change in pressure there is no effect on the reaction or in reactant and product concentrations. However if volume decreases, and there are more moles of gas on the left (reactant side) then the reaction will shift right (towards the product). But if the volume decreases and the are more moles of gas on the right (product side), then the reaction will shift to the left (reactant side).

Ryan Yee 1J
Posts: 101
Joined: Sat Aug 17, 2019 12:16 am

Re: Changes in Pressure

Postby Ryan Yee 1J » Thu Jan 23, 2020 10:16 pm

Increasing pressure by decreasing the volume will cause a shift to the side with fewer moles of gas, and decreasing pressure by increasing volume causes a shift to the side with more moles of gas. If you change the pressure by adding an inert gas into the system, then nothing changes.

Ariel Davydov 1C
Posts: 110
Joined: Thu Jul 11, 2019 12:16 am
Been upvoted: 1 time

Re: Changes in Pressure

Postby Ariel Davydov 1C » Fri Jan 24, 2020 10:29 am

In order to determine how a change in pressure affects the equilibrium of a system, it must be said how the pressure was changed in the first place. As the above comments said, if the pressure is increased by adding an inert gas, there will be no change in equilibrium, since the partial pressures of the system remain unaffected. If the pressure is changed by changing the volume, you must calculate the new concentrations of the reactants and products, calculate Q, and compare it to K in order to see which way the reaction will shift. If the pressure is changed by increasing or decreasing the partial pressure of a reactant or product, the reaction will shift just as if you had increased or decreased the concentration of the same reactant or product. Hope this helps!

MAC 4G
Posts: 121
Joined: Wed Sep 18, 2019 12:16 am

Re: Changes in Pressure

Postby MAC 4G » Fri Jan 24, 2020 10:48 am

I had a similar question and I'm not sure if it's right, but when I looked it up, it said that increasing the pressure, the reaction will shift towards the side with fewer moles of gas. And just the opposite for a decrease in pressure.

Leonardo Le Merle 1D
Posts: 56
Joined: Wed Feb 27, 2019 12:16 am

Re: Changes in Pressure

Postby Leonardo Le Merle 1D » Fri Jan 24, 2020 12:15 pm

It is important to note that PV=nRT only stands true if the increase in pressure changes concentration; adding an inert gas such as helium to the system will increase the pressure but make the volume remain the same, thus no change in K occurs.

Ayushi2011
Posts: 101
Joined: Wed Feb 27, 2019 12:17 am

Re: Changes in Pressure

Postby Ayushi2011 » Fri Jan 24, 2020 12:17 pm

Increasing pressure shifts the reaction to the side with the fewer moles of gas according to Le Chatelier's principle.

Jocelyn Thorp 1A
Posts: 103
Joined: Wed Sep 18, 2019 12:20 am

Re: Changes in Pressure

Postby Jocelyn Thorp 1A » Fri Jan 24, 2020 1:36 pm

if the pressure is changed without a change in volume (i.e. by adding an inert gas), then the reaction does not shift. If it is changed due to a volume change, then the reaction will favor the side with the fewest overall moles of gas.

Elizabeth Harty 1A
Posts: 125
Joined: Sat Jul 20, 2019 12:16 am

Re: Changes in Pressure

Postby Elizabeth Harty 1A » Fri Jan 24, 2020 1:47 pm

It has to have an effect on volume to effect the direction but it doesn't effect equilibrium constant.

CameronDis2K
Posts: 51
Joined: Wed Feb 20, 2019 12:18 am

Re: Changes in Pressure

Postby CameronDis2K » Fri Jan 24, 2020 2:01 pm

Increasing the pressure will in turn decrease the volume of the container in which the specimens are contained: the side with less moles of gas favored as there are fewer molecules on that side of the reaction = smaller volume.


Return to “Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions”

Who is online

Users browsing this forum: No registered users and 1 guest