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F = ma

The second Physics concept we need has to do with force. When a force is applied to an object, the object will accelerate unless there is another equal force to offset it. The acceleration is measured as a change in either the speed of the object or its direction or both. The amount of acceleration depends on the mass of the object: the heavier the object, the less it accelerates. Newton’s law tells us that the force F applied to an object is equal to the acceleration of the object a times its mass m :

Using these two equations, we will be able to relate the pressure of a gas to the mass of the gas particles and their acceleration when they hit the walls of the container. This means that, in principle, we should be able to find the pressure of a gas from the properties and movements of the gas particles. However, in a typical sample of a gas there might be a mole or many moles of particles. Understanding the motions of 10 23 or more molecules will require some interesting observations and some very careful thinking about how to interpret these observations.

Observation 1: the limitations of the ideal gas law

One of the amazing things about the Ideal Gas Law is that it predicts exactly the same pressure for every type of gas. If we know the temperature of the gas, the volume it is contained in, and the number of moles of the gas, then we can predict its pressure without even knowing what type of gas we have. This is very surprising. We know about the structure and bonding of molecules and we know some of the properties of molecules that the structure and bonding create. These properties vary a lot from one molecule to the next. In the Foundations, we learned that the pressure of a gas must be somehow related to the movement of the gas particles. It would seem that different molecules would move differently and this would cause different pressures. But this is not the case.

This suggests that we should look for experimental conditions where the pressures of different gases are different. In other words, we need to find conditions where the predictions of the Ideal Gas Law aren’t correct. If we can find such conditions, we would find that P is no longer equal to nRT/V . One way to do this is to plot P versus nRT/V for a gas: we can vary n , V , and T and look at how P changes. Rather than vary all three variables at the same time, we’ll take a fixed T and vary the “particle density,” n/V . We can increase n/V by either pumping in more gas to increase n or by decreasing the volume of the container. Either way, we only have one variable to look at, which is the density of particles in the container. If we plot P versus nRT/V , we should get a straight line, since the Ideal Gas Law predicts that these are always equal to each other. This straight line should be exactly the same for all gases under all conditions if the Ideal Gas Law is valid. The results of such an experiment are shown in Figure 1 for three different gases.

These data show two features which should catch your eye. The first is that all three graphs look very much like the straight line predicted by the Ideal Gas Law even when we increase the density of particles by a factor of 10. Therefore, the Ideal Gas Law works really well even when we increase the density of the gas by quite a lot. The second feature, however, is that if we look very closely at the three graphs for the three different gases at the highest density, we see that the pressures start to vary away from the Ideal Gas Law and away from each other. This is a little hard to see in Figure 1, so we’ll try plotting the data more clearly in Figure 2. This time, we will plot the ratio PV/nRT versus n/V . If the Ideal Gas Law works, then PV/nRT should always be equal to 1. If not, PV/nRT will be something different than 1, either higher or lower. This means that measuring PV/nRT in an experiment is a way for us to tell whether the Ideal Gas Law is valid.

Questions & Answers

how can chip be made from sand
Eke Reply
is this allso about nanoscale material
are nano particles real
Missy Reply
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
where is the latest information on a no technology how can I find it
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
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
has a lot of application modern world
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
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
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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