# 0.2 Phase equilibrium and intermolecular interactions  (Page 6/7)

 Page 6 / 7

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.

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 can chip be made from sand
is this allso about nanoscale material
Almas
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!