# 0.18 Reaction equilibrium in the gas phase  (Page 3/6)

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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 ${n}_{{\text{N}}_{2}{\text{O}}_{4}}$ ${P}_{{\text{N}}_{2}{\text{O}}_{4}}$ (atm) ${P}_{\text{N}{\text{O}}_{2}}$ (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 .

We test this in [link] by plotting ${P}_{\text{N}{\text{O}}_{2}}$ 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 ${P}_{{\text{N}}_{2}{\text{O}}_{4}}$ increases close to proportionally with the initial amount of N 2 O 4 . This suggests plotting ${P}_{\text{N}{\text{O}}_{2}}$ versus the square root of ${P}_{{\text{N}}_{2}{\text{O}}_{4}}$ . 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

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yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
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da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
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Alexandre
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Rafiq
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Damian
How we are making nano material?
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What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
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