Boiling pt in a vacuum

[skywalker70]

Good day all

 

I need a list of boiling points of various elements in a vacuum but keep coming up with nothing on Google. Any help or pointers to reliable sources is apprecaited.

 

Thanks

[studiot]

Good day all

 

I need a list of boiling points of various elements in a vacuum but keep coming up with nothing on Google. Any help or pointers to reliable sources is apprecaited.

 

Thanks

 

Considering the definition of boiling point

 

The temperature at which the vapour pressure of the liquid is equal to the pressure of the gas above it

 

the question has no meaning in a vacuum.

[skywalker70]

Good point. Thanks for replying. But how does a comet's coma start to form? As far as I am aware as comets drop in nearer to the Sun they start to vaporize, forming the tail. It is in that sense that I am looking.

[studiot]

Good point. Thanks for replying. But how does a comet's coma start to form? As far as I am aware as comets drop in nearer to the Sun they start to vaporize, forming the tail. It is in that sense that I am looking.

 

 

I am not an astrophysicist, perhaps one here will answer authoritatively.

 

Meanwhile look up sublimation of ice, which I believe is the process you seek.

 

https://en.wikipedia.org/wiki/Sublimation_(phase_transition)

[Janus]

Here's a phase diagram for water

 

 

Note that at 1 pascal, the sublimation point is at ~-60C. 1 pascal is technically considered a high vacuum. Conditions in space allow for a better vacuum than this, but it will at least give you a general idea.

[swansont]

Note that at 1 pascal, the sublimation point is at ~-60C. 1 pascal is technically considered a high vacuum. Conditions in space allow for a better vacuum than this, but it will at least give you a general idea.

 

 

A nit here. 1 pascal is medium vacuum (aka crappy vacuum, at least in my lab, and I think they're a little high with the division at 0.1 pascal)

I wouldn't think about starting an ion pump at that pressure, unless I was trying to kill it.

 

Anyway, we get solids giving gas at those temperatures under high vacuum. Cs, Rb, K, I, Hg, Te and Ca are all ones I've used, and plenty of others are available. Spectroscopy cells, and I've laser-trapped Cs and Rb from vapor in vacuums.