[zmasterflex]

I'm getting conflicting info regarding the "critical temperature."
Is it "where liquid doesn't exist anymore," or where "no phase boundaries exist."
Both are definitions I found on the web and both are choices as an answer. I would think that the second one is more is exact but the first one is labeled as correct.... any input would give clarity. thanks

[Radu]

At a temperature equal or greater than the critical temperature, no matter how much pressure you applied, you will never get a condensed(liquid) phase. That's the physical meaning. Mathematically, I am not sure if P-T curve simply vanishes or it abruptly approaches zero. I'd go for the first one, though.( They are made considering dP/dT=Δ_rH/RT², which cannot raise to infinity , for the function to descend steeply)