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It is important to note that we can vary the relative amount ofNH 3 produced by varying the temperature of the reaction, the volume of the vessel in which the reaction occurs, or the relative startingamounts of N 2 and H 2 . We shall study and analyze this observation in detail in latersections. For now, though, we demonstrate that the concept of reaction equilibrium is general to all reactions.

Consider the reaction

H 2 ( g ) + I 2 ( g ) 2 H I ( g )

If we begin with 1.00 mole of H 2 and 1.00 mole of i 2 at 500 K in a reaction vessel of fixed volume, we observe that, at equilibrium, n H I 1.72 mol , leaving in the equilibrium mixture n H 2 0.14 mol and n I 2 0.14 mol .

Similarly, consider the decomposition reaction

N 2 O 4 ( g ) 2 N O 2 ( g )

At 298K in a 100.0L reaction flask, 1.00 mol ofN 2 O 4 partially decomposes to produce, at equilibrium, n N O 2 0.64 mol and n N 2 O 4 0.68 mol .

Some chemical reactions achieve an equilibrium that appears to be very nearly complete reaction. Forexample,

H 2 ( g ) + Cl 2 ( g ) 2 H Cl ( g )

If we begin with 1.00 mole of H 2 and 1.00 mole of Cl 2 at 298K in a reaction vessel of fixed volume, we observe that, at equilibrium, n H Cl is almost exactly 2.00 mol, leaving virtually no H 2 or Cl 2 This does not mean that the reaction has not come to equilibrium. It means instead that, at equilibrium, there are essentially noreactants remaining.

In each of these cases, the amounts of reactants and products present at equilibrium vary as theconditions are varied but are completely reproducible for fixed conditions. Before making further observations that will lead to aquantitative description of the reaction equilibrium, we consider a qualitative description of equilibrium.

We begin with a dynamic equilibrium description. We know from our studies of phase transitions thatequilibrium occurs when the rate of the forward process ( e.g. evaporation) is matched by the rate of reverse process ( e.g. condensation). Since we have now observed that gas reactions also come to equilibrium, we postulate that at equilibrium the forwardreaction rate is equal to the reverse reaction rate. For example, in the reaction here , the rate of decomposition ofN 2 O 4 molecules at equilibrium must be exactly matched by the rate ofrecombination (or dimerization ) of NO 2 molecules.

To show that the forward and reverse reactions continue to happen at equilibrium, we start with theNO 2 and N 2 O 4 mixture at equilibrium and we vary the volume of the flask containing the mixture. We observe that, if we increase the volumeand the reaction is allowed to come to equilibrium, the amount of NO 2 at equilibrium is larger at the expense of a smaller amount of N 2 O 4 . We can certainly conclude that the amounts of the gases atequilibrium depend on the reaction conditions. However, if the forward and reverse reactions stop once the equilibrium amounts ofmaterial are achieved, the molecules would not "know" that the volume of the container had increased. Since the reactionequilibrium can and does respond to a change in volume, it must be that the change in volume affects the rates of both the forward andreverse processes. This means that both reactions must be occurring at equilibrium, and that their rates must exactly match atequilibrium.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
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
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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.
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
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
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 ?
Bob Reply
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?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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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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