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Affichage des articles dont le libellé est Chimie. Afficher tous les articles
Affichage des articles dont le libellé est Chimie. Afficher tous les articles

vendredi 27 juillet 2012

Chemistry Chimie كيمياء

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للتحميل من FilesIn  : مستعملي IDMAN يفضل تعطيله


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1- Softwares


In construction




2- Learning by Simulations


To be continued


5- Overlapping Chromatographic Peaks



In chromatography a common problem is the correct quantification of overlapping peaks. Given that the two peaks are both at the baseline of the chromatogram, the separation of the two peaks (and the subsequent quantification) is performed by selecting the minimum between the two peaks as the separation line. While this approach is quite reliable if the peaks have the same height, it becomes more and more prone to considerable errors if the heights of the two peaks do not match (which is the common case).

This program simulates the quantification error made when dealing with chromatographics peaks of unequal height. The user may experiment with different peak positions, heights and peak widths. 



Download:

English version http://aa.vg/ljtihlkbm4fr [323kB] 
German version http://aa.vg/5h37z1jqo4hr [324 kB] 




4- Sector Field MS




The magnetic sector field is - among other principles such as electric quadrupole fields, or flight time measurements - one of the most often used principles for commerical mass spectrometers. The principle is easy to understand: a beam of accelerated ions is directed into a magnetic field whose orientation is perpenticular to the beam. The magnetic field thus forces the charged particles on different circular trajectories, whose radii depend on the strength of the magnetic field, the accelerating voltage, and on the mass of the particular ion.
Keeping all but the magnetic field constant results in a separation of the ions according to their mass. Since the detector has a narrow entry split, it "sees" only a small fraction of the entire ion beam fan, i.e. those ions which travel along the circular trajectory connecting both the exit slit of the ion source and the entry slit of the detector. All other ions collide with the inner wall of the evacuated separation system (a small rectangular tube of non-magnetic material). 

The program ms_sectorfield simulates the separation of ions of different masses in a magnetic sector field. The user can adjust both the accelerating voltage and the magnetic field strength, and select from a small number of substances, whose mass spectra have been provided by NIST (courtesy S. Stein of NIST). 


Download:

English version http://aa.vg/iz7oj31slij5 [387 kB] 
German version http://aa.vg/uafqqzczjd66 [387 kB] 




3- Atomic Spectra




Atomic spectra may be used to quantitatively determine more than 70 chemical elements. In order to be able to detect the atomic spectrum, the atoms or ions have to be separated from one another, i.e. the atoms have to be in a gaseous state. This can be achieved by massively heating the substances to be determined (typically the temperature is several thousand degrees). When the gas heats up, it emits light of various characteristic wavelengths. For hydrogen the resulting spectrum obeys a very simple relation:
where ni and nf are positive non-zero integers with ni > nf and RH is a constant called Rydberg's constant:
RH = 1.097107 m-1.
Apart from chemical analysis atomic spectroscopy is of considerable importance for the investigation of stars, looking for elemental compositions which could enable life in some form. The interest in atomic emission and absorption lines can be traced back to the late 18th and the early 19th Century when Fraunhofer discovered dark lines in the spectrum of the sun light.

 f you would like to experiment with spectral lines of selected elements, you can use the program AtomSpec which allows the user to select from several chemical elements. The spectrum may be zoomed to view details of the atomic spectral lines.


Download:

English version http://aa.vg/615593albvgh [266 kB] 
German version http://aa.vg/hr3n6bwkylxx [266 kB] 



2- Molecular Formulas




    If we know the molecular weight of a substance we implicitely know the atomic composition of that substance - provided that the molecular weight is known to an accuracy which is sufficient to distinguish between molecules having the same nominal mass.
To explain this, let's have a look at a very simple example: suppose we know that our substance has a molecular weight of 28. A quick calculation (considering only the nominal masses of the most abundant isotopes of carbon, hydrogen, oxygen, and nitrogen - 12, 1, 16, and 14, respectively) shows that there are three substances which all have the same molecular mass of 28: C2H4 (ethene), CO (carbon monoxide) and N2 (nitrogen gas).

Now, the important point is not to forget that the nominal masses are just for convenience. The actual masses of the four elements are:







12C = 12.00000
1H = 1.007825037
16O = 15.99491464
14N = 14.003074
From this you can easily calculate that the actual molecular masses of the three substance having a nominal mass of 28 are:
  • C2H4 = 28.031300148
  • N2 = 28.006148
  • CO = 27.99491464
The smallest difference between the three masses is between CO and N2, showing a diffence of 0.0112 mass units. In other words, if we know the molecular mass to an accuracy of 0.0056 masses (half the minimum difference) we can easily distinguish between the three molecules having a nominal mass of 28.
This simple example shows the principle of finding the atomic composition by means of mass spectrometry. You simply have to determin the mass with an accuracy high enough to reduce the number of possible candidates to a single molecule. Of course, in practice the molecular masses of interest are much higher and the number of possible candidates increases exponentially if we do not take countermeasures, such as a chemical plausibility check. 

The program MolForm allows to calculate all possible molecular formulas of a particular mass. The user may set the molecular mass and its tolerance (accuracy). This example shows the possible formulas for molecules containing C, H, O, N, and Cl atoms.


Download:
English version http://aa.vg/vwod418b55lv  [266 kB] 
German version http://aa.vg/33gbd30pv3jq [266 kB] 



1- Console of a Mass Spectrometer







A mass spectrometer is a device which can perform accurate chemical analysis (both quantitative and qualitative). Although there are several different technical implementations (sector field, quadrupole, time of flight) all of these devices are based on the same idea: the molecules under investigation are first broken up and then the type and the amount of fragments are investigated. The kind of fragments provides information on the chemical structure of the original molecule, the amount of fragmented ions allows to determine the quantities. Regardless of the actual ionisation and separation technique all kinds of mass spectrometers eventually yield a mass spectrum, which is a line spectrum showing the fragment mass on the x-axis and the number of generated ions on the y-axis.


  This program ms_scope simulates the console of a mass spectrometer. The user may experiment with different resolutions and mass ranges. Ambient air, pregnene, 6-methyl-5-nonen-4-one and perfluorokerosene may be put into the simulated mass spectrometer.


Download:
 English version http://aa.vg/onx29mileq95 [263 kB] 
German version http://aa.vg/yjw5v3v5m11h [264 kB] 





3- Books



English


To be continued



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6- Macrocyclic Chemistry: New Research Developments



 
Daniel W. Fitzpatrick, Henry J. Ulrich, "Macrocyclic Chemistry: New Research Developments"
English | 2010 | ISBN: 1608768961 | 517 pages | PDF | 6,9 MB


A macrocycle is, as defined by IUPAC, 'a cyclic macromolecule or a macromolecular cyclic portion of a molecule'. In the chemical literature, organic chemists may consider any molecule containing a ring of seven or more atoms to be a macrocyle. Co-ordination chemists generally define a macrocycle more narrowly as a cyclic molecule with three or more potential donor atoms that can co-ordinate to a metal centre. This book brings together the latest research results from around the world.
 

  Lynda.com - Project Management Fundamentals


or




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5- Workbook for Organic Chemistry




Jerry Jenkins, "Workbook for Organic Chemistry"
English | 2009 | ISBN: 1429247584 | 512 pages | PDF | 3,9 MB


Jerry Jenkins’ extensive workbook provides approximately 80 problems per topic with full worked out solutions. The perfect aid for students in need of more problem-solving, the Workbook for Organic Chemistry can be paired with any organic chemistry text on the market. For instructors interested in online homework, W.H. Freeman has also placed these problems in WebAssign.


 Lynda.com - Project Management Fundamentals


or




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4- Inspection, Prevention, Control, and Repair of Corrosion
Avionics Equipement

Link:   http://www.filesin.com/4023D216773/download.html

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3- Handbook of chemistry

 Link: http://www.restfile.com/zwjtdss7w9ah/chem-v1.pdf.html

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2- The Chemistry of Paints and Painting 
    is a free textbook on chemical aspects of painting. This ebook is based on the printed copy of a book written by Sir Arthur H. Church in 1915. approx. 180 pages, 10 figures

 2.2 MB


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1-  General Chemistry
    is a free textbook on the fundamentals of chemistry This book is currently under construction.

 2.2 MB



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عــربـــــــــــيــة

 يــتــبــع 

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8- السلامة_في_المختبرات_الكيميائية
http://www.restfile.com/matp7ej6dntc/السلامة_في_المختبرات_الكيميائية.pdf.html

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7- أساسيات_الكيمياء_الفيزيائية-عملي
http://www.restfile.com/01bv85tx0mgv/أساسيات_الكيمياء_الفيزيائية-عملي.pdf.html

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6- أساسيات_الكيمياء_الفيزيائية-نظري
http://www.restfile.com/zz8afo8wwvhp/أساسيات_الكيمياء_الفيزيائية-نظري.pdf.html

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 5- أساسيات_الكيمياء_العضوية-عملي

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4- أساسيات_الكيمياء_العضوية_-_نظري

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3- الكيمياء_العامة
http://www.restfile.com/58gk4qlb2zge/الكيمياء_العامة.pdf.html

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2- أساسيات الكيمياء التحليلية - عملي.pdf
http://www.restfile.com/2k5evmviluup/Basic_Anal_Chem_Pratique.pdf.html

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1- أساسيات الكيمياء التحليلية - نظري.pdf
http://www.restfile.com/jel5sk529lue...Theor.pdf.htm