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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.


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.

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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
characteristics of micro business
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 ?
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.
what is the actual application of fullerenes nowadays?
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.
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.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Concept development studies in chemistry. OpenStax CNX. Dec 06, 2007 Download for free at http://cnx.org/content/col10264/1.5
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