Freezing a chemical equilibrium
Suppose you have a system in chemical equilibrium, and you start to cool down (you withdraw heat energy).
Normally, and according to the rules of Le Chatellier and van 't Hoff the equilibrium will suffer a shift, a dislocation:
The exothermic reactin (producing energy) will occur extra.
But this is not all there is: adapt to any change always costs some time.
Cooling down means for the participating particles that they will move more slowly, and their vibration will also slow down.
Every reaction has its own minimum temperature. Below that temp the reaction does not occur.
But imagine now that you cool down the equilibrium in no timme: within a couple of second the temperature decreases very much
(the substances suddenly are thrown in ice, or worse: in liquid Nitrogen).
Then the system has no time to quietly adapt itself to the new situation. The particles immediately lose their movement.
The particles have no longer sufficient energy to participate in the reaction.
If that happens: an reaction in equilibrium is cooled down very quickly, then we say:
the equilibrium was frozen.
The forward and the backward reaction both stop in one moment, and have no time to adapt to the changing circumstances.
Products as well as reactants suddenly reach a temperature under their minimum.
After stopping the reactions, also the concentrations do not longer suffer any change. There is no longer a dynamic equilibrium.
Bacteria do practically not change when quickly frozen.
All substances remain in not changing concentration and the metabolism remains closed at that cold.
After starting heating carefully, many reactions slowly will retake their activity. The bacteria come back to life.
There are people that want to apply this phenomena to themselves: make yourself deeply frozen before dying.
Who knows, you could wake up in a hundred years, if new drugs are found for your illness, after being warmed up carefully.
What do you think of that? Technically as well as ethically?