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### Topic: critical temperature & pressure  (Read 8929 times)

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##### critical temperature & pressure
« on: November 10, 2006, 07:21:44 AM »
I want to know what is critical temperature, and pressure, it's the term often used, for steam and liquid too. Can any one explain it to me briefly?
what the difference b/w Normal temperature and pressure, standard temperature pressure,
in one case the temperature is taken as 60 F, in the other case it's taken as 25 C.
What is meant by superheated steam? how one can define superheated steam at 120 oC.

#### AWK

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##### Re: critical temperature & pressure
« Reply #1 on: November 10, 2006, 07:39:21 AM »
AWK

#### eugenedakin

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##### Re: critical temperature & pressure
« Reply #2 on: November 11, 2006, 01:40:22 AM »

http://en.wikipedia.org/wiki/Critical_temperature

Essentially, here is a way of explaining critical temperature:

Tc (Critical Temperature), of a material is the temperature above which distinct liquid and gas phases do not exist. As the critical temperature is approached, the properties of the gas and liquid phases become the same. Above the critical temperature, there is only one phase: that of supercritical fluid. The critical pressure is the vapor pressure at the critical temperature. The critical molar volume is the volume of one mole of material at the critical temperature and pressure. On diagrams showing thermodynamic properties for a given substance, the point at critical temperature and critical pressure is called the critical point of the substance. Above its critical temperature, a gas cannot be liquefied.

I hope this helps,

Eugene
There are 10 kinds of people in this world: Those who understand binary, and those that do not.

#### jebosa1

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##### Re: critical temperature & pressure
« Reply #3 on: November 18, 2006, 05:47:12 PM »
Water exhibits particularly unusual behaviour beyond its critical temperature and pressure (374Â° C, 218 atmospheres). Above its critical temperature, the distinction between the liquid and gaseous states of water disappearsâ€”it becomes a supercritical fluid, the density of which can be varied from liquidlike to gaslike by varying its temperature and pressure.