Gedankenexperiment in thermodynamics: what is wrong?

Good day.

A notion of chemical potential teaches us, that a chemical reaction

$A+B \to C$

at finite tempereture actually goes in both directions

$A+B \rightleftharpoons C$

and the intensity of a given diection depends on:

1) Temperature

2) Energy difference E(A+B) versus E(C)

For my argument it is enough that it exists in both directions. Let me assume A, B and C are gasses and A has the smallest molecules, B intermadiate and C the biggest ones.

I put A,B,C in a box and an quilibrium settles. Then I use a molecular sieve to extract A, I prevent A from going back to the box by using a vacuum-cleaner. A new equilibrium with excess of B comes into the place. I use (for a differential time where no more A passes) a molecular sieve with bigger holes to extract B. Then alternating sieves frequently I extract A and B, colling down the pool.

Is that possible?

I think it contradicts the second law of thermidynamics... I create A and B by cooling the pool. Then I can combust A and B....

Let us say $A=H_2$, $B=O_2$ and $C=H_20$ - it would lead to "energyless" dissociation of water.

What is wrong with my arguments? :

• "Bothdirectional" chemical reactions are a fact.

• Existence of molecular sieves is a fact...

Thanks

• @F.Jatpil it might become more apparent if you think of the question "is there a way to take two boxes at temperatures $T_1 > T_2$ and somehow increase $T_1$ by introducing a box at $T_3 = 0,$ as in absolute zero?". The question is answered clearly as "yes, a heat engine from box 2 to box 3 clearly produces work which can be fed to a heat pump from box 2 to box 1, increasing $T_1.$" This is not a violation of the second law of thermodynamics precisely because box 3 increases its entropy even if it is large enough to not change its temperature substantially. Feb 14, 2017 at 16:03