The discussion centers on the conditions under which iron can exist as a gas without transitioning into plasma, as well as the solidification of noble gases like neon and helium. Participants explore the definitions and properties of gases, plasmas, and solids, including temperature and pressure influences.
Participants express uncertainty regarding the transition between gas and plasma states and the conditions for noble gases to solidify. Multiple competing views remain on these topics, and the discussion does not reach a consensus.
Participants reference the first ionization energy of iron and the critical pressure of helium, indicating that the discussion relies on specific definitions and conditions that may not be universally agreed upon.
CthlhuLies said:Also, can something like a noble gas become a solid?
dauto said:Sure. Neon, for instance turns solid at about 24.5 K.
CthlhuLies said: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
The critical pressure of helium is 2.24 atm., so the equilibrium vapor pressure at the solidification temperature is lower than this.dauto said: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
There is no clear border between gas and plasma - if you increase the temperature, you just increase the fraction of ionized atoms.CthlhuLies said: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?
Where is the relation between the critical pressure (=gas/liquid related) and the solid phase?Chestermiller said:The critical pressure of helium is 2.24 atm., so the equilibrium vapor pressure at the solidification temperature is lower than this.
Yikes. I've never seen a phase diagram like this before. I guess you learn something new every day. Thanks.mfb said: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