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equilibrium constant

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GCT:

--- Quote from: ksr985 on May 15, 2005, 02:38:44 PM ---ahh.. exactly. i dont even know if all the A will decompose, that is also uncertain. all i know is that eqbm cannot be acieved. who's to say what position the reaction will occupy at any given time.

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Well, it'll depend on the temperature and the size of the container.  You can calculate whether all of A will decompose simply by using PV=nRT.  If some solid were to remain, then at equilibrium you would know that the pressure is 5 atm.

Borek:

--- Quote from: ksr985 on May 15, 2005, 01:56:57 PM ---BUT, the reaction cant end until eqbm is reached. there is no end to a reversible reaction. there is simply eqbm., the minimum in the free energy curve.the eqbm is dynamic, with the backward and forward reaction happening simultaneously. do you see why this is so weird?
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The answer is: reaction CAN end before the equilibrium is reached. Is there a solid in the equilibrium with the non-saturated solution? No. In the solution cotaining EDTA but no Mg(2+) is there an equilibrium with MgEDTA complex? No.

Other example, without a chemical reaction, but the idea remains the same: liquid water is in equilibrium with gaseus water. Get a drop of water and put into small container - there is liquid, there is gas, there is equilibrium. Make the container very large. All water is in the form of gas. Is there an equilibrium between liquid and gas? No. If the given equilibrium can't be reached due to lack of reagents system will be in other equilibrium, period.

ksr985:
yup. but the question remains unanswered, since keeping the volume of the container constant for the two experiments,ie, with 100 atm of A, and with 2 atm of A, we cannot reach eqbm in the latter, which should not happen. all reversible reactions must attain eqbm.

ksr985:
very, very good! i think i got it, finally. thanks a lot, man.

GCT:

--- Quote from: ksr985 on May 15, 2005, 02:48:24 PM ---yup. but the question remains unanswered, since keeping the volume of the container constant for the two experiments,ie, with 100 atm of A, and with 2 atm of A, we cannot reach eqbm in the latter, which should not happen. all reversible reactions must attain eqbm.

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Yes, equilibrium will not be reached in the latter...because it does not apply in this case.  It's simple logic, you'll need to have adequate amounts of A in order for equilibrium to be relevant.  I don't exactly understand why you're saying "it should not happen."

You need to think outside the box, it similar to Ksp, where Ksp pertains to saturation of the ionic compound.  If You provide too little of the ionic compound, all of it will dissolve in a large volume of water.  

In effect, equilibrium is not like maxwell's equations, it is a practical mathematical tool, not a sacred principle.

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