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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.

Instrumentation

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

Hydrocarbons

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

how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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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
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Yasmin
what is the function of carbon nanotubes?
Cesar
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
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AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
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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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