# 0.12 Phase equilibrium and intermolecular interactions

 Page 1 / 7

## Foundation

The "phase" of a substance is the particular physical state it is in. The most common phases are solid, liquid,and gas, each easily distinguishable by their significantly different physical properties. A given substance can exist indifferent phases under different conditions: water can exist as solid ice, liquid, or steam, but water molecules are ${H}_{2}O$ regardless of the phase. Furthermore, a substance changes phase without undergoing any chemical transformation: the evaporation ofwater or the melting of ice occur without decomposition or modification of the water molecules. In describing the differingstates of matter changes between them, we will also assume an understanding of the principles of the Atomic Molecular Theory and the Kinetic Molecular Theory . We will also assume an understanding of the bonding, structure, and properties of individual molecules.

## Goals

We have developed a very clear molecular picture of the gas phase, via the Kinetic Molecular Theory. The gasparticles (atoms or molecules) are very distant from one another, sufficiently so that there are no interactions between theparticles. The path of each particle is independent of the paths of all other particles. We can determine many of the properties of thegas from this description; for example, the pressure can be determined by calculating the average force exerted by collisionsof the gas particles with the walls of the container.

To discuss liquids and solids, though, we will be forced to abandon the most fundamental pieces of the KineticMolecular Theory of Gases. First, it is clear that the particles in the liquid or solid phases are very much closer together than theyare in the gas phase, because the densities of these "condensed" phases are of the order of a thousand timesgreater than the typical density of a gas. In fact, we should expect that the particles in the liquid or solid phases areessentially in contact with each other constantly. Second, since the particles in liquid or solid are in close contact, it is notreasonable to imagine that the particles do no interact with one another. Our assumption that the gas particles do not interact isbased, in part, on the concept that the particles are too far apart to interact. Moreover, particles in a liquid or solid mustinteract, for without attractions between these particles, random motion would require that the solid or liquid dissipate or fallapart.

In this study, we will pursue a model to describe the differences between condensed phases and gases and todescribe the transitions which occur between the solid, liquid, and gas phases. We will find that intermolecular interactions play themost important role in governing phase transitions, and we will pursue an understanding of the variations of these intermolecularinteractions for different substances.

## Observation 1: gas-liquid phase transitions

We begin by returning to our observations of Charles' Law . Recall that we trap an amount of gas in a cylinder fitted with a piston, and we apply afixed pressure to the piston. We vary the temperature of the gas, and since the pressure applied to the piston is constant, thepiston moves to maintain a constant pressure of the trapped gas. At each temperature, we then measure the volume of the gas. From ourprevious observations, we know that the volume of the gas is proportional to the absolute temperature in degrees Kelvin. Thus agraph of volume versus absolute temperature is a straight line, which can be extrapolated to zero volume at 0K.

Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
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
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
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.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
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
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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!