[Zensation]

Many high temperature reactions result in the breaking-deformation of molecules. Pressure and Temperature are supposedly directly correlated, but a high pressure reaction wouldn't act exactly like a high temperature reaction, would it? In a high temperature reaction, aren't the molecules physically moving with more energy? While in a high pressure reaction they are just more close together in a confined space?

It would seem that both pressure and temperature speed up reaction times but by different mechanisms. Is this a correct assumption? Or would a high pressure reaction break molecules just as easily by the same mechanism as a very high temperature reaction?

[curiouscat]

P & T work in different ways. If a reaction needed very high activation energy T provides it. P wouldn't. P is more useful for gas phase reactions where moles change.

[Zensation]

That's what I initially thought. Wasn't entirely sureee.... thank you!

[Zensation]

Here's a question


Based on what you said, pressure cannot provide activation energy, but it can accelerate the speed at which reactions occur?

Suppose there is some molecule, that would fall apart at very high temperatures. Imagine it does perfectly fine under 50PSI of pressure. What about under 500PSI of pressure? 5000? Is there a point at which the pressure would destroy it? Or would the gas in the pressurized vessel just go to liquid after the pressure rises so much, not having much effect on the molecule other than the standard reaction at that temperature?

[curiouscat]

Guess it's  possible but I don't know of any.

Maybe a rxn. like   n G  G1 with large n. Somewhere where mole reduction happens.

[Zensation]

Okay. I had to ask because I recall seeing some paper saying that during some pressurized reaction, if the pressure exceeds a certain point then byproducts and degradation products would form, or it implied this at least.

[Borek]

Is there a point at which the pressure would destroy it?

Definitely. Think cold neutron star.

Or would the gas in the pressurized vessel just go to liquid after the pressure rises so much

Or solid, or will become supercritical, depending on the temperature and substance properties.

[Corribus]

Pressure dependence of reaction rate on condensed phase reactions is usually weak over most commonly encountered pressure ranges (i.e., small ones)*, but pressure dependence of gas phase reactions is high. Can you think of why?

(*Going from 50 psi to 5000 psi is not a small pressure change, and so I'd expect there to be a significant change in the reaction outcome.)