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Topic: Le Chatier's Principle with Pressure  (Read 1167 times)

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Offline zmasterflex

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Le Chatier's Principle with Pressure
« on: March 04, 2014, 10:27:11 AM »
The Question reads ---> Consider this equilibrium:
2SO2(g) + O2(g) --> 2SO3(g)
The forward reaction is proceeding at a certain rate at some temperature and pressure. When the pressure is increased, what might one expect for the forward reaction?

I assumed that the forward reaction would decrease in rate. This is because of Le Chatier's principle. 3 moles of reactant vs. 2 moles of products. We want more moles of gas (more disorder) so the pressure should push the reaction backwards. Therefore the forward reaction should slow down. The ACS book says that "increasing the pressure also increases the concentrations of the SO2 and O2 driving the reaction forward." Can someone please explain this to me? Thanks

Offline Kate

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Re: Le Chatier's Principle with Pressure
« Reply #1 on: March 04, 2014, 10:45:49 AM »
Le Chatelier's principle states that when you increase the pressure, the reaction will proceed in the direction that reduces the amount of gas that forms.

If it proceeded in the other direction, then there would be 2 sources of increased pressure: the initial pressure the system is subjected to and the one resulting from the increase in gas molecules formed.

So in your example, the forward reaction increases in rate.

The last sentence doesn't make sense to me though.

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