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Topic: Le Chatelier's Principle  (Read 8153 times)

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Offline VanKwisH

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Le Chatelier's Principle
« on: June 20, 2010, 02:42:26 AM »
Is the statement true or false, with respect to the specified reaction in each case?


1)
2SO3(g)= 2SO2(g) + O2(g)
If a vessel, containing an equilbrium mixture of these gases, is pressurized by adding argon gas, then the equilibrium position will shift to the right.   


2)
H2(g) + F2(g)= 2HF(g)
If an equilbrium mixture of these gases is released into a vessel of larger volume, then the equilibrium position will not shift.   


3)
Fe3+(aq) + SCN-(aq)= FeSCN2+(aq)
If this solution, at equilibrium, is diluted by adding water, then the equilibrium position will shift to the left.   


4)
H2O(g) + CO(g)= H2(g) + CO2(g)
If H2O gas is removed from an equilbrium mixture of these gases, then the equilibrium position will shift to the right.   


5)
H2O(g) + CO(g)= H2(g) + CO2(g) (Exothermic)
If the temperature is increased, then the equilibrium constant for this reaction equation will increase.   

I have
1)False - Because Inert gases do not affect the direction of the reaction
2)False - A increase in volume DOES affect the direction of the reaction, in this case to the left
3)True - Increasing the volume of a gas equilibrium is like increasing the amount of water containing an aqueous equilibrium; you can cause shifts in the direction of more ions
4)False - This should cause a shift to the left, because it wants to create more H2O to replace the concentration that was lost
5)False - If temp is increase, Keq should decrease ( according to my book )

Apparently it's wrong. It's multiple choice and i have to get all of them correct in order to get the mark. Which ones are wrong ? I've already tried but for some reason I can't seem to get which one are true/false.

Offline Borek

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Re: Le Chatelier's Principle
« Reply #1 on: June 20, 2010, 03:56:42 AM »
Please elaborate on 2nd.
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Offline bronstedlowry

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Re: Le Chatelier's Principle
« Reply #2 on: June 30, 2010, 12:13:25 AM »
1. True- the added pressure shifts the reaction to the side of the equation with less moles of gas.
2. True- the added volume has no effect on the equation, since there are an equal number of moles of gas on each side.
3. True- since the ion concentration decrease, the equation shifts to the left to make up for it.
4. False- the reaction will shift to the left to make up for the removed water vapor.
5. False- since the reaction is exothermic, the reaction shifts back to the left when heat is added.

Offline Abstractineum

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Re: Le Chatelier's Principle
« Reply #3 on: June 30, 2010, 03:40:58 AM »
1. True- the added pressure shifts the reaction to the side of the equation with less moles of gas.
2. True- the added volume has no effect on the equation, since there are an equal number of moles of gas on each side.
3. True- since the ion concentration decrease, the equation shifts to the left to make up for it.
4. False- the reaction will shift to the left to make up for the removed water vapor.
5. False- since the reaction is exothermic, the reaction shifts back to the left when heat is added.

Thing is, that the partial pressures of the reactants will not be altered by adding an inert gas. So it is not comparable to increasing the pressure by decreasing the volume (as the partial pressures of the reactants would then be higher).

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