Changing Pressure

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Olivia Young 1A
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Joined: Fri Sep 28, 2018 12:24 am

Changing Pressure

Postby Olivia Young 1A » Tue Jan 22, 2019 11:38 am

Is there any difference in the direction of the reaction when pressure is changed by altering the volume compared to adding inert gas?

Emmaraf 1K
Posts: 94
Joined: Sat Oct 20, 2018 12:16 am

Re: Changing Pressure

Postby Emmaraf 1K » Tue Jan 22, 2019 11:43 am

Yes, changing the volume is like compressing/decompressing the container which the reaction is taking place so pressure and volume have an inverse relationship. A decrease in volume is an increase in pressure and an increase in volume is a decrease in pressure. Therefore a volume decrease/pressure increase shifts to the side of less moles and a volume increase/pressure decrease goes to the side of more moles. You can also understand this by realizing that a decrease in volume causes and increase in concentration (moles/liter(aka a volume measurement)) on the side with more moles so the reaction will shift to the other direction.

Dong Hyun Lee 4E
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Joined: Fri Sep 28, 2018 12:23 am

Re: Changing Pressure

Postby Dong Hyun Lee 4E » Sun Jan 27, 2019 5:31 am

The direction of a reaction can change due to a change in volume (pressure). Using Le Chatleier principle, the equation will favor whatever side has less moles

Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: Changing Pressure

Postby katie_sutton1B » Sun Jan 27, 2019 10:19 am

You want to look at which side has less moles of gas, once it is equilibrium and balanced. Increasing the pressure forces the reaction to decrease the amount of moles, therefore going towards whichever direction has the least amount of moles. And vice versa for decreasing pressure

Matthew Choi 2H
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Joined: Fri Sep 28, 2018 12:18 am

Re: Changing Pressure

Postby Matthew Choi 2H » Sun Jan 27, 2019 4:39 pm

Inert gases do not react with the reactants nor the products, so it doesn't really have any effect on the concentrations of either. However, when you change the volume, then you can figure out which reaction will be favored by looking at the number of moles on both sides of the reaction.

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Joined: Wed Nov 15, 2017 3:03 am

Re: Changing Pressure

Postby uhedlund » Sun Jan 27, 2019 8:27 pm

Changing the volume results in a change in pressure. If the volume is decreased on one side of the reaction, the reaction will likely favor the other side if the pressure is lower. The reaction will favor the side with lower pressure in this case.

Riley Dean 2D
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: Changing Pressure

Postby Riley Dean 2D » Thu Jan 31, 2019 6:06 pm

Concentration is calculated by mol/L so if you change the volume it will cause a change in concentrations and therefore a shift in equilibrium, but if you dont change the volume and just pump in inert gas then the reaction will stay the same because none of the variables within the equation for concentration have changed

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