## Conditions favoring production - pressure

Anne Cam 3A
Posts: 71
Joined: Fri Sep 25, 2015 3:00 am

### Conditions favoring production - pressure

For the equation 2SO3(g) <---> 2SO2(g) + O2(g) which requires heat, it makes sense that increasing the temperature would favor SO2 production. But why is it that low pressure (instead of high) also favors production of SO2? Is it related to how many types of gases are present on each side of the equation?

Deanna Necula 3B
Posts: 62
Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

Yes, there are in total 2 moles on the left side of the equation and three on the right. Therefore, there will be a greater perceived pressure on the right side than on the left, because when you decrease the volume (which is how we're assuming we increase pressure because otherwise the change in pressure won't affect the equilibrium state) the more molecules you have the greater the likelihood it will collide with the walls of the container and generate increased pressure. Therefore, because you have more moles on the right than on the left, there will a greater perceived pressure on the right side of the equation than on the left when you increase pressure, so the reaction will proceed backwards and form the reactants in order to reach the equilibrium state. Therefore, in order to allow the reaction to proceed in the forward direction, you must lower the pressure.

Melissa Kulon 2D
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Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

So does any change in pressure (an increase or decrease) result in favoring the side with the fewer amount of moles?

Brandon Truong 2G
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Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

An increase in pressure would result in favoring the side with fewer moles while a decrease in pressure would result in favoring the side with more moles. This is assuming that the change in pressure is done by changing the volume of the system and not by adding inert gases.

Anne Cam 3A
Posts: 71
Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

So what would happen if inert gases were added to the reaction? Would that have no effect on the equilibrium whatsoever?

Ankur Sharma 3J
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Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

Anne Cam 3A
I believe that inert gasses, would hinder (maybe even prevent) association, and increases dissociation. At a constant pressure I know that the inert gas will increase the volume, and at a constant volume the total pressure will increase.

Laila Sathe 1D
Posts: 27
Joined: Fri Sep 25, 2015 3:00 am

### Re: Conditions favoring production - pressure

Actually, adding inert gasses has no effect on the equilibrium. As Dr. Lavelle mentioned, changing pressure changes concentrations and concentrations are then what affects the equilibrium position. When you add an inert gas, there is NO change to the concentrations of reactants (total volume and moles of Rs&Ps do not change) and products and therefore equilibrium is NOT affected.

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