<< Chapter < Page Chapter >> Page >

is still not a complete phase diagram, because we have not includedthe combinations of temperature and pressure at which solid and liquid are at equilibrium. As a starting point for theseobservations, we look more carefully at the conditions near 0°C. Very careful measurements reveal that the solid-gasline and the liquid-gas line intersect in where the temperature is 0.01°C. Under these conditions, we observe inside thecontainer that solid, liquid, and gas are all three at equilibrium inside the container. As such, this unique temperature-pressurecombination is called the triple point . At this point, the liquid and the solid have the same vapor pressure,so all three phases can be at equilibrium. If we raise the applied pressure slightly above the triple point, the vapor must disappear.We can observe that, by very slightly varying the temperature, the solid and liquid remain in equilibrium. We can further observe thatthe temperature at which the solid and liquid are in equilibrium varies almost imperceptibly as we increase the pressure. If weinclude the solid-liquid equilibrium conditions on the previous phase diagram, we get this , where the solid-liquid line is very nearly vertical.

Phase diagram of water

Each substance has its own unique phase diagram, corresponding to the diagram in for water.

Observation 4: dynamic equilibrium

There are several questions raised by our observations of phase equilibrium and vapor pressure. The first wewill consider is why the pressure of a vapor in equilibrium with its liquid does not depend on the volume of the container intowhich the liquid evaporates, or on the amount of liquid in the container, or on the amount of vapor in the container. Why do weget the same pressure for the same temperature, regardless of other conditions? To address this question, we need to understand thecoexistence of vapor and liquid in equilibrium. How is this equilibrium achieved?

To approach these questions, let us look again at the situation in . We begin with a container with a fixed volume containing some liquid,and equilibrium is achieved at the vapor pressure of the liquid at the fixed temperature given. When we adjust the volume to a largerfixed volume, the pressure adjusts to equilibrium at exactly the same vapor pressure.

Clearly, there are more molecules in the vapor after the volume is increased and equilibrium is reestablished,because the vapor exerts the same pressure in a larger container at the same temperature. Also clearly, more liquid must haveevaporated to achieve this equilibrium. A very interesting question to pose here is how the liquid responded to the increase in volume, which presumably only affected the space in which the gas moleculesmove. How did the liquid "know" to evaporate when the volume was increased? The molecules in the liquid could not detectthe increase in volume for the gas, and thus could not possibly be responding to that increase.

The only reasonable conclusion is that the molecules in the liquid were always evaporating, even before thevolume of the container was increased. There must be a constant movement of molecules from the liquid phase into the gas phase.Since the pressure of the gas above the liquid remains constant when the volume is constant, then there must be a constant numberof molecules in the gas. If evaporation is constantly occurring, then condensation must also be occurring constantly, and moleculesin the gas must constantly be entering the liquid phase. Since the pressure remains constant in a fixed volume, then the number ofmolecules entering the gas from the liquid must be exactly offset by the number of molecules entering the liquid from the gas.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Concept development studies in chemistry. OpenStax CNX. Dec 06, 2007 Download for free at http://cnx.org/content/col10264/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Concept development studies in chemistry' conversation and receive update notifications?

Ask