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It is helpful to think again about the analogy of people in a large open space. If the space is large enough and people wander randomly in the space, then they will almost never chance across each other and therefore almost never interact with each other. In this case, it would not matter to any individual in the space whether the other people in the room were friendly or unfriendly, passive or aggressive. Each person would move just as if she or he were the only person in the room.

Our conclusion, then, is that the particles in a gas are so far apart from one another that they move independently of each other, with no interactions or forces between them which might have created either attractions or repulsions. We say that there are no “intermolecular forces” or “intermolecular interactions.”

Postulates of the kinetic molecular theory

We are now ready to assemble a model to explain our observations in the Ideal Gas Law. Remember that we are trying to explain a macroscopic observation, in this case the pressure of a gas, using molecular properties or motions. So we capture the molecular concepts we developed in the three observations into a set of “postulates”:

  • A gas consists of individual particles in constant and random motion.
  • The distance (on average) between particles is very much larger than the sizes of individual particles.
  • Because of the large distances between particles, the individual particles (on average) do not exert any forces on each other, so that they neither attract nor repel one another.
  • The pressure of the gas is due entirely to the force of the collisions of the gas particles with the walls of the container.

Note that all of these postulates come from our analysis of experimental observations. And in turn, this model can be used to understand most of our observations of the properties of gases. With some extra work and additions, this model is also quite useful in understanding properties of liquids and solids as well.

The ideal gas law and the kinetic molecular theory

We know from our observations that the pressure of a gas decreases with volume, increases with temperature, and increases with the number of particles. To complete our connection between molecular properties and motions and experimental observations, we need to show that the postulates above lead us to the Ideal Gas Law. Notice that our postulates don’t say anything about temperature. We will have to deal with that later. First, we will show how the pressure of a gas is related to the number of particles and the volume.

A detailed derivation using Physics and Mathematics is possible, but for our purposes, we will focus on the concepts. First, we know that the pressure of the gas results from the force of collisions of the gas molecules with the walls of the container. Pressure is force divided by area, so we will focus only the force of the molecules hitting a small area, probably the surface of our pressure gauge. We can call that area A . The force F is the mass of the particles hitting the wall multiplied by the acceleration resulting from the particles hitting the wall. What is that acceleration? In the easiest case, we might imagine that a particle hitting the wall keeps all of its energy and simply changes its direction. Then the acceleration is simply the change from its speed v to the same speed in the reverse direction –v , so the acceleration is proportional to 2v and the force of each impact is proportional to 2mv . This makes sense: the faster the particles are moving, the greater their acceleration when they hit the wall, the greater the force they create. And the greater the mass of each particle, the greater the force of each impact.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
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 2013. OpenStax CNX. Oct 07, 2013 Download for free at http://legacy.cnx.org/content/col11579/1.1
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