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For example, in the reaction [link] , the stoichiometry is determined as shown in [link] and [link] .

However, as calculated this reaction would be for the reaction in an environment of pure oxygen. On the other hand, air has only 21% oxygen (78% nitrogen, 1% noble gases). Therefore, if air is used as the oxidizer, this must be taken into account in the calculations, i.e., [link] .

The mole fractions for a stoichiometric mixture in air are therefore calculated in following way: [link] - [link] ).

Calculate the fuel mole fraction (xfuel) for the stoichiometric reaction:

In this reaction ν = 2, as 2 moles of oxygen are needed to fully oxidize methane into H 2 O and CO 2 .

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Calculate the fuel mole fraction for the stoichiometric reaction

The fuel mole fraction is 4.03%.

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Premixed combustion reactions can also be characterized by the air equivalence ratio, λ, as shown in [link] .

The fuel equivalence ratio, Φ, is the reciprocal of this value [link] .

Rewriting [link] in terms of the fuel equivalence ratio gives: [link] - [link] .

The premixed combustion processes can also be identified by their air and fuel equivalence ratios ( [link] ).

Identification of combustion type by Φ and λ values.
Type of combustion Φ λ
Rich >1 <1
Stoichiometric =1 =1
Lean <1 >1

With a premixed type of combustion, there is much greater control over the reaction. If performed at lean conditions, then high temperatures, the pollutant nitric oxide, and the production of soot can be minimized or even avoided, allowing the system to combust efficiently. However, a premixed system requires large volumes of premixed reactants, which pose a fire hazard. As a result, nonpremixed combusted, while not being efficient, is more commonly used.


Though the instrumentation of combustion analysis has greatly improved, the basic components of the apparatus ( [link] ) have not changed much since the late 18th century.

Combustion apparatus from the 19 th century. The Oesper Collections in the History of Chemistry, Apparatus Museum, University of Cincinnati, Case 10, Combustion Analysis. For a 360 o view of this apparatus, visit (External Link) .

The sample of an organic compound, such as a hydrocarbon, is contained within a furnace or exposed to a flame and burned in the presence of oxygen, creating water vapor and carbon dioxide gas ( [link] ). The sample moves first through the apparatus to a chamber in which H 2 O is absorbed by a hydrophilic substance and second through a chamber in which CO 2 is absorbed. The change in weight of each chamber is determined to calculate the weight of H 2 O and CO 2 . After the masses of H 2 O and CO 2 have been determined, they can be used to characterize and calculate the composition of the original sample.

Typical modern combustion apparatus with a furnace.

Calculations and determining chemical formulas


Combustion analysis is a standard method of determining a chemical formula of a substance that contains hydrogen and carbon. First, a sample is weighed and then burned in a furnace in the presence of excess oxygen. All of the carbon is converted to carbon dioxide, and the hydrogen is converted to water in this way. Each of these are absorbed in separate compartments, which are weighed before and after the reaction. From these measurements, the chemical formula can be determined.

Questions & Answers

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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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advantages of NAA
Sai Reply
how I can reaction of mercury?
Sham Reply

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Source:  OpenStax, Physical methods in chemistry and nano science. OpenStax CNX. May 05, 2015 Download for free at http://legacy.cnx.org/content/col10699/1.21
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