Exploring Plasma, Iron & Noble Gases: Temperature & Solid State

[CthlhuLies]

The way I understand plasma is that is almost a gas except some of the electrons of separated from the nuclei entirely making positively charged. Is there a temperature in which Iron is by definition a gas, and not a plasma?

Also, can something like a noble gas become a solid?

 

[dauto]

Also, can something like a noble gas become a solid?

Sure. Neon, for instance turns solid at about 24.5 K.

 

[CthlhuLies]

Sure. Neon, for instance turns solid at about 24.5 K.

Would this have to be under pressure or could it be 24.5 kelvin in a vacuum and still be a solid?

Also nice job on the 700 posts :D

 

[dauto]

Would this have to be under pressure or could it be 24.5 kelvin in a vacuum and still be a solid?

Also nice job on the 700 posts :D

That's at standard pressure. Only helium does not turn solid at standard pressure. If memory serves, a minimum of 20 atmospheres is required (and extremely low temperatures) to produce solid helium

 

[Chestermiller]

That's at standard pressure. Only helium does not turn solid at standard pressure. If memory serves, a minimum of 20 atmospheres is required (and extremely low temperatures) to produce solid helium

The critical pressure of helium is 2.24 atm., so the equilibrium vapor pressure at the solidification temperature is lower than this.

Chet

 

[mfb]

The way I understand plasma is that is almost a gas except some of the electrons of separated from the nuclei entirely making positively charged. Is there a temperature in which Iron is by definition a gas, and not a plasma?

There is no clear border between gas and plasma - if you increase the temperature, you just increase the fraction of ionized atoms.
The first ionization energy of iron is 8 eV and iron becomes a gas at ~3000K or ~1/4 eV, at this temperature the fraction of ionized atoms is low (but still existent).

The critical pressure of helium is 2.24 atm., so the equilibrium vapor pressure at the solidification temperature is lower than this.

Where is the relation between the critical pressure (=gas/liquid related) and the solid phase?

Here is a phase diagram of helium

 

[Chestermiller]

There is no clear border between gas and plasma - if you increase the temperature, you just increase the fraction of ionized atoms.
The first ionization energy of iron is 8 eV and iron becomes a gas at ~3000K or ~1/4 eV, at this temperature the fraction of ionized atoms is low (but still existent).

Where is the relation between the critical pressure (=gas/liquid related) and the solid phase?

Here is a phase diagram of helium

Yikes. I've never seen a phase diagram like this before. I guess you learn something new every day. Thanks.

Chet