Vapour Pressure

Vapor pressure - Wikipedia, the free encyclopedia

explain to me"in detail" why you're to lazy to just do an internet search yourself.

Your dog doesn't want to do your homework for you:

And neither do we.

No. Do research, reflect, think about it, think some more. Search, search again for information. If you do all that, and still have a question, dial us up then.

http://en.wikipedia.org/wiki/Critical_point_%28thermodynamics%29

As a new Poster you might not be familiar with the number one reason why many do not reply to posts such as yours.

For my particular reason. I do not do other's homework. Why should I do your work and not get a grade for it?

It's been a long time since I had to do your sort of homework, perhaps I am the world's wizard in the subject or I could be some venomous despicable misfit who wants to make it sound like I am an authority. How do you know? You have to make the choice. Likewise you have to do your own homework instead of wondering if I am either exceedingly smart or someone whose only intent is to make you get a failing grade!

Good Luck, Old Salt

Dear Mr.LTamilselvan,

Your quiery is "Is it possible for a fliud to have more than one critical pressure.?

The answer is NO. Only one Critical Pressure exists.

DHAYANANDHAN.S

dhayanandhan, I must respectfully disagree. Do you know about the Frenkel Line?

It sounds very much like anther homework matter fom here....

You are referring to this:

Two liquid states of matter: a dynamic line on a phase diagram.

Brazhkin VV, Fomin YD, Lyapin AG, Ryzhov VN, Trachenko K. Source

Institute for High Pressure Physics RAS, 142190 Troitsk Moscow Region, Russia. brazhkin@hppi.troitsk.ru

Abstract

[It is generally agreed that the supercritical region of a liquid consists of one single state (supercritical fluid). On the other hand, we show here that liquids in this region exist in two qualitatively different states: "rigid" and "nonrigid" liquids. Rigid to nonrigid transition corresponds to the condition τ≈τ(0), where τ is the liquid relaxation time and τ(0) is the minimal period of transverse quasiharmonic waves. This condition defines a new dynamic crossover line on the phase diagram and corresponds to the loss of shear stiffness of a liquid at all available frequencies and, consequently, to the qualitative change in many important liquid properties. We analyze this line theoretically as well as in real and model fluids and show that the transition corresponds to the disappearance of high-frequency sound, to the disappearance of roton minima, qualitative changes in the temperature dependencies of sound velocity, diffusion, viscous flow, and thermal conductivity, an increase in particle thermal speed to half the speed of sound, and a reduction in the constant volume specific heat to 2k(B) per particle. In contrast to the Widom line that exists near the critical point only, the new dynamic line is universal: It separates two liquid states at arbitrarily high pressure and temperature and exists in systems where liquid-gas transition and the critical point are absent altogether. We propose to call the new dynamic line on the phase diagram "Frenkel line".] endquote

However, this is in reference to two liquid states at high pressure and temperature, and has nothing to do with the vapor state, or the critical point where there is no distinction between liquid and vapor. The donkey needs to put nose in corner.

Thank you Mr. 1capybara for your guidance.

I got some reference in google search, and I will study the same. If you consider water ( I am not sure whether I am correct) the critical pressure is 3206 psi or 220.45 Kg/cm^2 is the critical pressure - only ONE VALUE.

DHAYANANDHAN.S

a newer abstract, published Auguest 2013

http://www.nature.com/ncomms/2013/130816/ncomms3331/full/ncomms3331.html

indicates that differences between vapor and liquid continue to exist, although it is on the molecular level. On the macro level, supercritical fluids work just fine, as in the supercritical coal power plants. The crossover between the two - (liquid like supercritical fluids and gas like supercritical fluids), is the Frenkel line. The Frenkel line is actually a fuzzy line or zone.

Mr. Stewart, your right, donkey's nose now in corner.

dhayanandhan -

You and Mr. Stewart are right, I did not understand and am now corrected.

There is one supercritical point. But above that, supercritical fluids can be either liquid like or gas like on a molecular level, depending if they are below or above he Frenkel line. On the macro level, such as in a supercritical coal plant, the difference between above and below the Frenkel line is not important. As best as i understand it.

re-quote from the previous article: ["the new dynamic line is universal: It separates two liquid states at arbitrarily high pressure and temperature and exists in systems where liquid-gas transition and the critical point are absent altogether. We propose to call the new dynamic line on the phase diagram "Frenkel line".]

read that and please do attempt to explain you line of reasoning once again to me. I myself have a problem with the statement that "liquid-gas transition AND the critical point are absent altogether. This goes outside the bar ditches of physics and physical chemistry as I have been taught. Every system wherein there is liquid does have a physical measureable vapor pressure. By the same reasoning, there will be a critical point where liquid and vapor are no longer distinguishable.

the current view is best summed up by wikipedia here:

https://en.wikipedia.org/wiki/Supercritical_fluid

"Dima Bolmatov, V. V. Brazhkin and K. Trachenko discovered that specific heat shows a crossover between two different dynamic regimes of the low-temperature rigid-liquid and high temperature non-rigid gas-like fluid.^[4] Rigid liquids are rigid like a solid on short time scales, but flow like a liquid on long time scales;^[5] while a supercritical gas-like fluid has the dynamic motions of a gas but is able to dissolve materials, like a liquid. The crossover challenges the currently held belief that no difference can be made between a gas and a liquid above the critical point and that the supercritical state is homogeneous in terms of physical properties."

what this means is

1. yes, the supercritical point still exists

2. increasing either pressure or temperature above that point is the supercritical fluid zone

3. that supercritical fluids in that zone are divided into two types by the Frenkel line, those more gas like and those more rigid liquid like.

4. the difference between the two types of supercritical fluids isn't relevant to their use in, for ex., todays working supercritical or ultra-supercritical coal plants, but may have future uses.

5. if you read other articles from these guys, in one they propose four different phases of solids. they are thinking and experimenting on the cutting edge.