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Topic: chemical equilibrium  (Read 3749 times)

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Offline Mppl

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chemical equilibrium
« on: June 18, 2010, 05:22:33 AM »
I have a question I suppose its obvious but I just can't figure out the solution:
In this reaction:
CaCO3(g)---CaO(s)+CO2(g)
we know that the overall pressure is 0.105 atm and the reaction takes place at constant temperature (350ºC)
The question is what's Kp and Kc

One thing i know for sure, Kc=Kp because we have same number of gas molecules in both sides of equation.
I know or i think i know is that pressure is constant or almost constant (because of the creation of the solid substance) during the reaction so i can easly calculate the initial number of molecules of the reagent.
I just don't reach the way of getting kp or Kc

If anyone could help me I would appreciate, thanks

Offline Borek

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Re: chemical equilibrium
« Reply #1 on: June 18, 2010, 06:22:45 AM »
One thing i know for sure, Kc=Kp because we have same number of gas molecules in both sides of equation.

Do we? I can't see a gas on the left. You may add (g) to everything, but it won't make it gaseous. Paper is patient, reality has its own ways.
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Offline Mppl

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Re: chemical equilibrium
« Reply #2 on: June 18, 2010, 06:36:36 AM »
CaCO3 decomposes as it reaches its boiling point (as far as i know), this reaction I posted describes precisely this, anyway  my aim here is not to see if what the exercise describes is possible, I'm just asking what would be the solution and as the book says it has one molecule of gas on the left and other on the right so pressure during the reaction will be almost constant and Kp=Kc in that case right?

Offline AWK

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Re: chemical equilibrium
« Reply #3 on: June 18, 2010, 06:46:31 AM »
A pressure 0.105 atm does not mean the boiling point of calcium carbonate
AWK

Offline Mppl

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Re: chemical equilibrium
« Reply #4 on: June 18, 2010, 06:59:23 AM »
well forget it anyway I don´t care if CaCO3 reaches its boiling point or not i have the equation I gave you, so abstract from the fact that CaCO3 shouldnt be in gas state I just want to know what the solution will be if it is possible, and how to get there,
thanks

Offline Borek

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Re: chemical equilibrium
« Reply #5 on: June 18, 2010, 07:08:35 AM »
If CaCO3 is assumed to be gaseous question has no solution. Question can be solved if we assume that CaCO3 is solid, but we can't assume that, as you told us not to. So I am afraid you are on your own now :P
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Offline Mppl

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Re: chemical equilibrium
« Reply #6 on: June 18, 2010, 09:59:45 AM »
well it seemed to me so, the book has a mistake then, i checked it and it has CaCO3 as a gas so probably is an error from book. Thanks for the help.

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