Molecularity in chemistry is the number of colliding molecular entity molecular entities that are involved in a single reaction step . ref GoldBookRef title molecularity url http goldbook.iupac.org M03989.html year 1996 ref While the order chemistry order of a reaction is derived experimentally, the molecularity is a theoretical concept and can only be applied to elementary reaction s. In elementary reactions, the reaction order chemistry order , the molecularity and the stoichiometric coefficient are the same, although only numerically, because they are different concepts. A reaction involving one molecular entity is called unimolecular. A reaction involving two molecular entities is called bimolecular. A reaction involving three molecular entities is called termolecular. Termolecular reactions in solution s or gas mixtures are very rare, because of the improbability of three molecular entities simultaneously collision frequency colliding ref http www.intute.ac.uk sciences reference plambeck chem2 p02156.htm Discussion on the improbability of termolecular reactions ref . However the term termolecular is also used to refer to three body association reactions of the type math A B overset M to C math Where the M over the arrow denotes that to conserve energy and momentum a second reaction with a third body is required. After the initial bimolecular collision of A and B an energetically excited reaction intermediate is formed, then, it collides with a M body, in a second bimolecular reaction, transferring the excess energy to it. ref Text discussing rate constant s for termolecular reactions http jpldataeval.jpl.nasa.gov pdf Jpl15 Sectn2 TermolecRxs.pdf ref The reaction can be explained as two consecutive reactions math A B to AB math math AB M to C M math These reactions frequently have a pressure and temperature dependence region of transition between second and third order kinetics. ref IUPAC definition of Troe expression , a semiempirical expression for the rate constant ... more details
The entropy of activation is one of the two parameters typically obtained from the temperature dependence of a reaction rate, when these data are analysed using the Eyring equation . Symbolized S sup sup , the entropy of activation provides clues about the molecularity of the rate determining step in a reaction, i.e. whether the reactants are bonded to each other, or not. Positive values suggest that entropy increases upon achieving the transition state, which often indicates a Dissociative substitution dissociative mechanism . Negative values for S sup sup indicate that entropy decreases upon achieving the transition state, which often indicates an Associative substitution associative mechanism . Values near zero are difficult to interpret. ref J. H. Espenson Chemical Kinetics and Reaction Mechanism McGraw Hill, 1981, ISBN 0 070019667 2. ref References references Category Chemical kinetics ... more details
Electron capture ionization is the ionization of a gas phase atom or molecule by attachment of an electron to create an ion of the form A sup sup . The reaction is math A e overset M to A math where the M over the arrow denotes that to conserve energy and momentum a third body is required the molecularity of the reaction is three . Electron capture can be used in conjunction with chemical ionization . ref Citation doi 10.1021 ac50035a017 title Electron capture negative ion chemical ionization mass spectrometry year 1978 author Donald F. Hunt Frank W. Crow journal Analytical Chemistry volume 50 issue 13 pages 1781 ref An electron capture detector is used in some gas chromatography systems. ref GoldBookRef title electron capture detector in gas chromatography file E01981 ref See also Electron capture dissociation References Reflist analytical chem stub Category Ion source ... more details
an elementary step, and each has its own rate law and molecularity . The elementary steps should add ... must be used. Molecularity main molecularityMolecularity in chemistry is the number of colliding ... more details
orphan date September 2010 Image Cuticura Soap Ad 1894.JPG thumb right 1894 Advertisement for Cuticura Soap from Good Housekeeping Magazine Cuticura soap is an antibacterial medicated soap , in use since 1865 manufactured by Potter Drug and Chemical Company, George Robert White owner. It contains triclocarban instead of the more usual triclosan . These two antibacterial agents have very similar molecularity. By themselves they kill 99.99 of bacteria and microbe s like fungus spores on contact. Cuticura soap has been in use, and is relatively unchanged, since 1865. In 1908 the British Medical Journal investigated the advertising of nostrums for the treatment of skin diseases. As reported by the American Medical Association ref cite book last first title Nostrums and Quackery publisher American Medical Association Press location Chicago year 1912 pages 594 url http books.google.com books?id 9gREAAAAIAAJ&pg PA594&dq cuticura soap&as brr 1 ref it was implied that Cuticura soap could be effective in the treatment of syphilis when prepared as an internal remedy known as Cuticura Resolvent . The medical community considered the proposed remedy to contain insufficient potassium iodide to be effective in the treatment of the disease. ref Nostrums p 595 ref In 1914 the Good Housekeeping Magazine ran an analysis of a large number of household products including Cuticura soap. They concluded that Cuticura was, A good grade of soap containing a small quantity of prussian blue and probably a little phenol . Prussian blue has been recommended for skin diseases. Excessive claims made for Cuticura as to the prevention and treatment of skin eruptions, are not warranted by its composition. ref cite book last Wiley first Harvey W title 1001 Tests of Foods, Beverages and Toilet Accessories, Good and Otherwise publisher Hearst s International Library Co location New York year 1914 pages 214 url http books.google.com books?id 181LAAAAIAAJ&pg PA214&dq 22potter drug 22 cuticura&as brr 1 PPA ... more details
merge to Energy medicine date May 2010 Energy therapy Vibrational medicine is an alternative therapy based on the belief that illness is caused by energy imbalances. The concept is based on the premise that Human body human bodies are made up of interconnectedness interconnected fields of putative not empirically observable Energy esotericism energy and that when a human body is not well that it is the result of one or more of these fields of energy being unbalanced ref Gerber, Richard, M.D. Vibrational Medicine Santa Fe, NM Bear & Company, 1988 ref ref Oschman, James L. Energy Medicine The Scientific Basis New York, Churchill Livingstone, 2000 . ref and that the re balancing of these esoteric energies will help to re establish a person s good health. Proponents hypothesize that disease within the physical body occurs at the cellular and Molecularity bimolecular levels. In vibrational medicine, healing is said to extend from the bimolecular level to the cellular and finally, to the anatomical. According to Hwaa Irfan , praying to Allah can help raise the vibration from negative to positive. ref http www.islamonline.net servlet Satellite?c Article C&cid 1157962517694&pagename Zone English HealthScience 2FHSELayout Vibrational Medicine And The Human Energy Field , Hwaa Irfan , Islam Online, 26 July 2001 ref Reputation and efficacy There is no scientific evidence that the energy fields that vibrational medicine is based upon exist, and therefore vibrational medicine is generally viewed as pseudoscience . It is not recognized in medical academia and has been described as the weirdest of New Age therapies . ref http www.telegraph.co.uk health main.jhtml?xml health 2004 01 23 hhurt23.xml Will this hurt? , The Daily Telegraph , 23 January 2004 ref References reflist External links http www.issseem.org The International Society for the Study of Subtle Energies and Energy Medicine http nccam.nih.gov health backgrounds energymed.htm NIH Energy medicine overview Category Energ ... more details
Unimolecular ion decomposition is the fragmentation of a gas phase ion in a reaction with a molecularity of one. ref Cite journal doi 10.1146 annurev.pc.30.100179.000411 title Unimolecular Ion Decomposition year 1979 last1 Brenton first1 A G last2 Morgan first2 R P last3 Beynon first3 J H journal Annual Review of Physical Chemistry volume 30 pages 51 ref Ions with sufficient internal energy may fragment in a mass spectrometer , which in some cases may degrade the mass spectrometer performance, but in other cases, such as tandem mass spectrometry , the fragmentation can reveal information about the structure of the ion. Wahrhaftig diagram File Wahrhaftig Diagram.gif thumb right 400 px Wahrhaftig diagram showing the relationship between internal energy and unimolecular ion decomposition for a hypothetical ion ABCD sup sup . A Wahrhaftig diagram illustrates the relative contributions in unimolecular ion decomposition of direct fragmentation and fragmentation following rearrangement. The x axis of the digram represents the internal energy of the ion. The lower part of the diagram shows the logarithm of the rate constant k for unimolecular dissociation whereas the upper portion of the diagram indicates the probability of forming a particular product ion. The green trace in the lower part of the diagram indicates the rate of the rearrangement reacton given by math ABCD to AD BC , math and the blue trace indicates the direct cleavage reaction math ABCD to AB CD , math A rate constant of 10 sup 6 sup s sup 1 sup is sufficiently fast for ion decomposition within the ion source of a typical mass spectrometer. Ions with rate constants less than 10 sup 6 sup s sup 1 sup and greater than approximately 10 sup 5 sup s sup 1 sup lifetimes between 10 sup 5 sup and 10 sup 6 sup s have a high probability of decomposing in the mass spectrometer between the ion source and the detector. These rate constants are indicated in the Wahrhaftig diagram by the log k 5 and log k 6 dashed lines. Indicated ... more details
were of the same molecularity , for instance if both involved collisions with the same reactant. ref ... if the overall transformations to each product were of the same molecularity , for instance ... more details
orders and depend on the reaction mechanism . Stoichiometry , molecularity the actual number of molecules ... molecules of type B n plus m is the molecularity . For gases the rate law can also be expressed in pressure ... more details
DISPLAYTITLE S sub N sub 1 reaction The S sub N sub 1 reaction is a substitution reaction in organic chemistry . S sub N sub stands for nucleophilic substitution and the 1 represents the fact that the rate determining step is molecularity unimolecular . ref L. G. Wade, Jr., Organic Chemistry , 6th ed., Pearson Prentice Hall, Upper Saddle River, New Jersey, USA, 2005 ref ref J. March, Advanced Organic Chemistry , 4th ed., Wiley, New York, 1992. ref The reaction involves a carbocation intermediate and is commonly seen in reactions of secondary or tertiary alkyl halide s under strongly basic conditions or, under strongly acidic conditions, with Alcohol Primary.2C secondary.2C and tertiary alcohols secondary or tertiary alcohols . With primary alkyl halides, the alternative SN2 reaction S sub N sub 2 reaction occurs. Among inorganic chemists, the S sub N sub 1 reaction is often known as the dissociative mechanism . A reaction mechanism was first proposed by Christopher Ingold et al. in 1940. ref Cite journal author Leslie C. Bateman, Mervyn G. Church, Edward D. Hughes, Christopher K. Ingold and Nazeer Ahmed Taher doi 10.1039 JR9400000979 title 188. Mechanism of substitution at a saturated carbon atom. Part XXIII. A kinetic demonstration of the unimolecular solvolysis of alkyl halides. Section E a general discussion year 1940 journal Journal of the Chemical Society Resumed pages 979 ref Mechanism An example of a reaction taking place with an S sub N sub 1 reaction mechanism is the hydrolysis of tert butyl bromide with water forming tert butyl alcohol Image ReakcjaSn1hydrolizabromkutertbutylowego.svg reaction tert butylbromide water overall This S sub N sub 1 reaction takes place in three steps Formation of a tert butyl carbocation by separation of a leaving group a bromide anion from the carbon atom this step is slow and reversible reaction reversible . ref Cite journal title Nature of Dynamic Processes Associated with the SN1 Reaction Mechanism author Peters, K. S. jour ... more details
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