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This reasoning reveals that the amounts of reactant and product present at equilibrium are determined by therates of the forward and reverse reactions. If the rate of the forward reaction ( e.g. decomposition ofN 2 O 4 ) is faster than the rate of the reverse reaction, then atequilibrium we have more product than reactant. If that difference in rates is very large, at equilibrium there will be much moreproduct than reactant. Of course, the converse of these conclusions is also true. It must also be the case that the rates of theseprocesses depends on, amongst other factors, the volume of the reaction flask, since the amounts of each gas present atequilibrium change when the volume is changed.

Observation 2: equilibrium constants

It was noted above that the equilibriumpartial pressures of the gases in a reaction vary depending upon a variety of conditions. These include changes in the initial numbersof moles of reactants and products, changes in the volume of the reaction flask, and changes in the temperature. We now study thesevariations quantitatively.

Consider first the reaction here . Following on our previous study of this reaction, we inject an initial amount ofN 2 O 4 (g) into a 100L reaction flask at 298K. Now, however, we vary theinitial number of moles of N 2 O 4 (g) in the flask and measure the equilibrium pressures of both thereactant and product gases. The results of a number of such studies are given here .

Equilibrium partial pressures in decomposition reaction
Initial n N 2 O 4 P N 2 O 4 (atm) P N O 2 (atm)
0.1 0.00764 0.033627
0.5 0.071011 0.102517
1 0.166136 0.156806
1.5 0.26735 0.198917
2 0.371791 0.234574
2.5 0.478315 0.266065
3 0.586327 0.294578
3.5 0.695472 0.320827
4 0.805517 0.345277
4.5 0.916297 0.368255
5 1.027695 0.389998

We might have expected that the amount of NO 2 produced at equilibrium would increase in direct proportion to increases in the amount ofN 2 O 4 we begin with. [link] shows that this is not the case. Note that when we increase the initial amountof N 2 O 4 by a factor of 10 from 0.5 moles to 5.0 moles, the pressure of NO 2 at equilibrium increases by a factor of less than 4.

The relationship between the pressures at equilibrium and the initial amount ofN 2 O 4 is perhaps more easily seen in a graph of the data in [link] , as shown in [link] . There are some interesting features here. Note that, when the initial amount ofN 2 O 4 is less than 1 mol, the equilibrium pressure of NO 2 is greater than that of N 2 O 4 . These relative pressures reverse as the initial amount increases,as the N 2 O 4 equilibrium pressure keeps track with the initial amount but the NO 2 pressure falls short. Clearly, the equilibrium pressure of NO 2 does not increase proportionally with the initial amount of N 2 O 4 . In fact, the increase is slower than proportionality, suggestingperhaps a square root relationship between the pressure of NO 2 and the initial amount of N 2 O 4 .

Equilibrium partial pressures in decomposition reaction

We test this in [link] by plotting P N O 2 at equilibrium versus the square root of the initial number of moles ofN 2 O 4 . [link] makes it clear that this is not a simple proportional relationship, but it is closer. Note in [link] that the equilibrium pressure P N 2 O 4 increases close to proportionally with the initial amount of N 2 O 4 . This suggests plotting P N O 2 versus the square root of P N 2 O 4 . This is done in [link] , where we discover that there is a very simple proportional relationshipbetween the variables plotted in this way. We have thus observed that

Questions & Answers

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.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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.
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
for teaching engĺish at school how nano technology help us
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
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?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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
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 2012. OpenStax CNX. Aug 16, 2012 Download for free at http://legacy.cnx.org/content/col11444/1.4
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