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Observation 1: limitations of the validity of the ideal gas law

To design a systematic test for the validity of the Ideal Gas Law , we note that the value of P V n R T , calculated from the observed values of P , V , n , and T , should always be equal to 1, exactly. Deviation of P V n R T from 1 indicates a violation of the Ideal Gas Law . We thus measure the pressure for several gases under a variety of conditions by varying n , V , and T , and we calculate the ratio P V n R T for these conditions.

Here , the value of this ratio is plotted for several gases as a function of the "particledensity" of the gas in moles, n V . To make the analysis of this plot more convenient, the particle density is given in termsof the particle density of an ideal gas at room temperature and atmospheric pressure ( i.e. the density of air), which is 0.04087 mol L . In this figure , a particle density of 10 means that the particle density of the gas is 10 times the particle density of air at roomtemperature. The x-axis in the figure is thus unitless.

Validity of the ideal gas law

Note that P V n R T on the y-axis is also unitless and has value exactly 1 for an ideal gas. We observe inthe data in this figure that P V n R T is extremely close to 1 for particle densities which are close to that of normal air. Therefore, deviations fromthe Ideal Gas Law are not expected under "normal" conditions. This is not surprising, since Boyle's Law , Charles' Law , and the Law of Combining Volumes were all observed under normal conditions. This figure also shows that, as the particle density increases above the normalrange, the value of P V n R T starts to vary from 1, and the variation depends on the type of gas we are analyzing. However, even forparticle densities 10 times greater than that of air at atmospheric pressure, the Ideal Gas Law is accurate to a few percent.

Thus, to observe any significant deviations from P V n R T , we need to push the gas conditions to somewhat more extreme values. The results for such extreme conditions areshown here . Note that the densities considered are large numbers corresponding to very high pressures. Under theseconditions, we find substantial deviations from the Ideal Gas Law . In addition, we see that the pressure of the gas (and thus P V n R T ) does depend strongly on which type of gas we are examining.Finally, this figure shows that deviations from the Ideal Gas Law can generate pressures either greater than or less than that predictedby the Ideal Gas Law .

Deviations from the ideal gas law

Observation 2: density and compressibility of gas

For low densities for which the Ideal Gas Law is valid, the pressure of a gas is independent of the nature of the gas, and is therefore independent of the characteristics of theparticles of that gas. We can build on this observation by considering the significance of a low particle density. Even at thehigh particle densities considered in this figure , all gases have low density in comparison to the densities of liquids. To illustrate,we note that 1 gram of liquid water at its boiling point has a volume very close to 1 milliliter. In comparison, this same 1 gram of water, onceevaporated into steam, has a volume of over 1700 milliliters. How does this expansion by a factor of 1700 occur? It is not credible that theindividual water molecules suddenly increase in size by this factor. The only plausible conclusion is that the distance betweengas molecules has increased dramatically.

Questions & Answers

Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
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.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
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Source:  OpenStax, General chemistry ii. OpenStax CNX. Mar 25, 2005 Download for free at http://cnx.org/content/col10262/1.2
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