Cold chemistry

[hypertilly]

What cold chemical substances (not as extreme as dry ice ) can be contained in a vacuum?

[YT2095]

not many (in fact NON that I can think of) things tend to Boil away in a vacuum.

 

are you sure you don`t mean under Positive Pressure?

[hypertilly]

Hi

Thanks for your reply.

Perhaps I have worded it badly-i'm very new to the study of chemistry.

Basically what I would like to get to grips with is, is are there any cold chemical substances which can be encased in a container.

Am I making anymore sense?

[YT2095]

there are Many, and because of their nature they have to be containerised as they would boil away at room temp and pressure.

a typical example is Butane gas (the sort used to fill cigarette lighters with), the can is at room temp, but when the liquid comes out it boils, and that evaporation by boiling causes freezing of whatever it`s in contact with.

[hypertilly]

Could you name some more of these?

[YT2095]

there`s a whole bunch of liquids that will boil at room temp and go to gas.

 

you just need to look up liquids with a BP less than 298k at 101kpa, it really is that simple

[hypertilly]

If butane gas is one of these such substances, why does a lighter (for example) not feel cold to the touch?

[YT2095]

because the liquid is at room temp like the rest of the lighter, BUT it`s also under a lot of pressure too (that`s what keeps it as a liquid).

[hypertilly]

What (unlike butane) would not stay at room temperature.

What would be cold to the touch?

[insane_alien]

nothing. it would evapourate until it reached a pressure where it can remain in vapour liquid equilibrium at room temperature. its only going to be old if you let it evapourate.

[hypertilly]

But if a cold chemical substance could be contained in some other other type of container and it was airtite, would it retain a dedree of coldness?

 

If so what....

[Cap'n Refsmmat]

No, not really. Unless the container was perfectly insulated, the material inside would warm up.

[insane_alien]

maybe if the laws of thermodynamics went on a nice little holiday to the maldives...

[hypertilly]

so it would be possible with the right substance.

But what substances would you suggest?

[insane_alien]

no, it wouldn't be possible with any substance at all, ever. there is no way to make a substance stay colder than its environment without either a chemical reaction(which would eventually reach equilibrium and warm up anyway) or a refridgeration cycle which dumps a lot of heat into the environment.