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Topic: Reaction


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In the News (Wed 19 Jun 13)

  
  Chemical reaction - Wikipedia, the free encyclopedia
A chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants.
Classically, chemical reactions encompass changes that strictly involve the motion of electrons, although the general concept of a chemical reaction (in particular the notion of a chemical equation) is applicable to transformations of elementary particles, as well as nuclear reactions.
Reaction rates are related to the concentrations of substances involved in reactions, as quantified by the law of mass action.
en.wikipedia.org /wiki/Chemical_reaction   (1242 words)

  
 Reaction - Wikipedia, the free encyclopedia
In physics, a reaction is defined by Newton's third law: "For every action there is an equal and opposite reaction".
In politics, the reaction is the attitude of the reactionaries, or their political movement.
In risk management, the reaction is a response after the hazard.
en.wikipedia.org /wiki/Reaction   (141 words)

  
 IodineClockReaction   (Site not responding. Last check: 2007-11-06)
For the reaction #'s 1 and 3 the concentration of hydrogen peroxide is the same but the concentration of the other reagent involved in the rate expression, the iodide ion, does vary.
In the reaction where the concentration of hydrogen peroxide (a molecular compound) is varied, the difference in the total volume of solution is compensated by the equivalent amount of another molecular compound, water.
In the reaction where the concentration of iodide ion is varied, the difference in total volume is compensated by the equivalent amount of another ion of the same charge, the chloride ion.
www.nv.cc.va.us /alexandria/science/IodineClockReaction.html   (1197 words)

  
 Visual Expert Human Factors: Driver Reaction Time
Reaction times are greatly affected by whether the driver is alert to the need to brake.
Reaction time depends to some extent on the distance to the obstacle and whether it is approaching from the side and is first seen in peripheral vision.
The increased reaction time is due to several factors, including the need to interpret the novel situation and possibly to decide whether there is time to brake or whether steering is better response.
www.visualexpert.com /Resources/reactiontime.html   (2987 words)

  
 R
In the formalism of "transition-state theory", the reaction coordinate is that coordinate in a set of curvilinear coordinates obtained from the conventional ones for the reactants which, for each reaction step, leads smoothly from the configuration of the reactants through that of the transition state to the configuration of the products.
An elementary reaction, constituting one of the stages of a stepwise reaction in which a reaction intermediate (or, for the first step, the reactants) is converted into the next reaction intermediate (or, for the last step, the products) in the sequence of intermediates between reactants and products.
The elementary reaction or reaction stage (of a molecular rearrangement) in which there is both making and breaking of bonds between atoms common to a reactant and a reaction product or a reaction intermediate.
www.chem.qmw.ac.uk /iupac/gtpoc/R.html   (2950 words)

  
 Maillard Reaction   (Site not responding. Last check: 2007-11-06)
Maillard reaction is a type of non-enzymatic browning which involves the reaction of simple sugars (carbonyl groups) and amino acids (free amino groups).
The initial reaction is the condensation of the carbonyl group of a reducing sugar (aldose) with a free amino group of a protein or an amino acid, which loses a molecule of water to form N-substituted glycosylamine (Step A).
In foods, attempts to prevent the reaction should be directed towards removing one of the reactants: the amino compounds (for carbohydrate-rich foods) or the reducing sugars for protein-rich foods.
www.landfood.ubc.ca /courses/fnh/410/colour/3_82.htm   (686 words)

  
 Grignard Reaction   (Site not responding. Last check: 2007-11-06)
The Grignard reaction is one of the characteristic reactions of carbonyl compounds.
Often reactions that look fine on paper fail to work in the laboratory, so it is important to have a back-up plan for making your target compound.
The Grignard reaction involves the nucleophilic attack of a carbanion (the Grignard reagent) on a carbonyl carbon.
www.sienahts.edu /~swathen/organic/grignard.html   (266 words)

  
 Herman Miller - for Business - Reaction Chairs
For active workers, Reaction moves fluidly and adjusts easily as the sitter shifts from forward sitting to reclined positions, from computer keyboard to phone to work surface.
Reaction is a low-priced, fully adjustable chair that has all the quality and function of a Herman Miller product, Caruso explains.
Reaction's back support lets the seat and back move in sync when the user reclines.
www.hermanmiller.com /CDA/SSA/Product/0,1592,a10-c440-p146,00.html   (470 words)

  
 Endothermic Reaction
The reaction that occurs is highly endothermic, and it causes the beaker to freeze to the board.
The gas produced by the reaction is shown to be basic by the use of pH paper.
The equation for the reaction shows that barium thiocyanate, ammonia gas, and liquid water are formed by the reaction of the solid barium hydroxide and the solid ammonium thiocyanate.
jchemed.chem.wisc.edu /JCESoft/CCA/CCA3/MAIN/ENDO2/PAGE1.HTM   (475 words)

  
 General Chemistry Online: Glossary: Reaction rates
The half life of a reaction is the time required for the amount of reactant to drop to one half its initial value.
The order of a reaction is the sum of concentration exponents in the rate law for the reaction.
A reaction with a rate law that is proportional to either the concentration of a reactant squared, or the product of concentrations of two reactants.
antoine.frostburg.edu /chem/senese/101/kinetics/glossary.shtml   (518 words)

  
 Chem4Kids.com: Reactions: Catalysts and Inhibitors
Reactions need a certain amount of energy to happen.
The energy a reaction needs is usually in the form of heat.
Catalysts lower the activation energy required for a reaction to occur.
www.chem4kids.com /files/react_catalyst.html   (317 words)

  
 Vaccine Reaction In A Dog at ThePetCenter.
Fortunately the vast majority of vaccine reactions in the dog are similar to this case where the targeted tissue is the skin.
When a reaction does occur, to revaccinate for the same diseases anytime later in the patient's life may be hazardous.
Where legally mandated vaccines are required, and your pet has had a reaction to the required vaccine, your veterinarian should be your advocate and write a statement on animal hospital letterhead that the patient should be exempt from subsequent vaccinations for the disease because of the potential for another vaccine induced reaction.
www.thepetcenter.com /exa/vacreact.html   (768 words)

  
 Chemical Kinetics: Rate of Reaction   (Site not responding. Last check: 2007-11-06)
The rate of reaction, r, is defined to be the slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that species.
Notice that this definition produces the same rate of reaction irrespective of which species in the reaction is used to perform the calculation.
As is evident from the above example, there is a relationship between the stoichiometric coefficient of a species in a reaction, the rate of change of the concentration of that species, and the rate of reaction.
www.chm.davidson.edu /ChemistryApplets/kinetics/RateOfReaction.html   (403 words)

  
 Chem4Kids.com: Reactions: Rates of Reaction
The rate of a reaction is the speed at which a reaction happens.
If a reaction has a low rate, that means the molecules combine at a slower speed than a reaction with a high rate.
The rate of reaction depends on the type of molecules that are combining.
www.chem4kids.com /files/react_rates.html   (365 words)

  
 F*A*C*T - REACTION-Web
This is especially useful if the reaction is in 'grams'.
Reaction calculates changes in extensive thermochemical functions (H, G, V, S, Cp, A) for a species, a group of species, or a chemical reaction.
Here, in Reaction-Web, the reaction is limited to isothermal standard state properties and the equilibrium constant, Keq.
www.crct.polymtl.ca /reacweb.htm   (282 words)

  
 orders of reaction and rate equations
For the purposes of rate equations and orders of reaction, the rate of a reaction is measured in terms of how fast the concentration of one of the reactants is falling.
This reaction is zero order with respect to A because the concentration of A doesn't affect the rate of the reaction.
This reaction is first order with respect to A and zero order with respect to B, because the concentration of B doesn't affect the rate of the reaction.
www.chemguide.co.uk /physical/basicrates/orders.html   (1313 words)

  
 RSI - Executive Recruiter & Executive Job Search Recruiting, Executive Search, Job Search Recruitment
Reaction Search can act as your executive recruiter to help you find highly-skilled personnel who will improve your company's competitive advantage.
Reaction Search is a nationwide executive search firm dedicated to identifying, evaluating, recruiting and delivering the highest-caliber professionals.
Reaction Search International is a leader in job assessment, recruiting, job search, executive search and headhunter services for your new career.
www.reactionsearch.com   (1152 words)

  
 SN2 Reaction Mechanism   (Site not responding. Last check: 2007-11-06)
Transition State: The transition state of the SN2 reaction is a trigonal bipyramid with partial bonds from the carbon atom to both the leaving group and the nucleophile.
Inversion of Configuration: The carbon is tetrahedral at the beginning and end of the reaction, but "umbrellas" in the middle so that the three hydrogen atoms which were pointing to the nucleophile end up pointing to the leaving group.
The left side of the reaction energy diagram, where the energy is the lowest, represents chloride ion and methylbromide prior to the reaction beginning.
www.chem.arizona.edu /courses/chem242/sn2.html   (408 words)

  
 Single Exchange Reactions; Thermite Reaction
The thermite reaction involves a mixture of iron oxide and aluminum that has been placed in a flower pot and covered with potassium permanganate.
When the product of the reaction is examined a large piece of white hot iron has fallen into the sand at the bottom of the apparatus.
The first step in the thermite reaction is oxidation of glycerine by potassium permanganate, which is demonstrated next.
jchemed.chem.wisc.edu /JCESoft/CCA/CCA1/R1MAIN/CD1R1870.HTM   (261 words)

  
 CHEMTUTOR REACTIONS   (Site not responding. Last check: 2007-11-06)
There are magnitudes of difference in the amounts of energy in ordinary chemical reactions compared to nuclear reactions, the rearrangement of the nuclei of atoms to change to new elements is enormous compared to the smaller energies of chemical changes.
Reversible reactions are symbolized in chemical equations by a double-headed arrow, but the standard remains to call the materials on the left the reactants and the materials on the right the products.
This type of reaction is called a replacement because a free element replaces one of the ions in a compound.
www.chemtutor.com /react.htm   (3274 words)

  
 Home
GUT REACTION was formed a decade ago in 1993-4 by a life-long sufferer of emetophobia, a fear of vomiting.
Gut Reaction was kindly granted permission to include a summary of her findings in the Autumn/Winter 2002 Newsletter and a full copy of her thesis is available on the
Gut Reaction is no longer a member organisation but copies of Newsletters and other files are now available on the Gut Reaction CD - See CD page for further details.
www.gut-reaction.freeserve.co.uk   (775 words)

  
 Organic Chemistry at Penn State: Reactions   (Site not responding. Last check: 2007-11-06)
Here is just a list of the reactions that we discussed in detail in class.
Please note that no stereochemistry is implied in the reaction schemes.
E1 mechanism for tertiary or secondary allylic or benzylic substrates: the leaving group departs in a unimolecular rate-limiting step, generating the carbocation, which in the second step is deprotonated (with base) on the carbon adjacent to the cationc center, yielding the olefin; carbocation rearrangements may compete
courses.chem.psu.edu /chem38/reactions/reactions.html   (982 words)

  
 REACTIONS & ENZYMES
Reactions that require energy to initiate the reaction are known as endergonic reactions.
In oxidation/reduction reactions, one chemical is oxidized, and its electrons are passed (like a hot potato) to another (reduced, then) chemical.
Reactions that show a net loss in energy are said to be exergonic; reactions that show a net gain in energy are said to be
www.emc.maricopa.edu /faculty/farabee/BIOBK/BioBookEnzym.html   (1582 words)

  
 HotAIR - Feline Reactions to Bearded Men   (Site not responding. Last check: 2007-11-06)
To ensure that the cats were not influenced by stroking or other unconscious cues from the assistant, the assistant was anesthetized prior to each session.
The cats' reactions were assessed for changes in pulse rate, respiration, eye dilation, fur shed rate, and qualitative behavior.
Because of Bork's distinctive beard, his photograph has been used in reaction studies with dogs, rats, and planaria (flatworms) and in bombardment studies with pigeons.
www.improb.com /airchives/classical/cat/cat.html   (1049 words)

  
 Newton's Third Law
These two forces are called action and reaction forces and are the subject of Newton's third law of motion.
The statement means that in every interaction, there is a pair of forces acting on the two interacting objects.
For every action, there is an equal (in size) and opposite (in direction) reaction force.
www.glenbrook.k12.il.us /gbssci/phys/Class/newtlaws/u2l4a.html   (734 words)

  
 CBC.ca - Canadian Adverse Drug Reaction Database - Disclaimer   (Site not responding. Last check: 2007-11-06)
CADRIS stands for Canadian Adverse Drug Reaction Information System and is used to monitor adverse drug reactions in drugs approved for the Canadian market.
Only a small proportion of suspected adverse reactions are reported to the program, consequently this information must not be used to estimate the incidence of adverse reactions.
A serious adverse drug reaction is defined as: A noxious and unintended response to a drug, which occurs at any dose and requires in-patient hospitalization or prolongation of existing hospitalization, causes congenital malformation, results in persistent or significant disability or incapacity, is life-threatening or results in death.
www.cbc.ca /news/adr/database   (1225 words)

  
 Allergic Reaction: Severe | AHealthyMe.com
Anaphylactic shock, or anaphylaxis, is one of the scariest health emergencies a parent can face; it occurs when your child has a severe allergic reaction.
Once your child has had a severe allergic reaction, your pediatrician may recommend that you keep an anaphylactic kit handy at all times.
Finally, once your child has a severe reaction like anaphylaxis, it's important for her to wear a medical-alert ID necklace or bracelet (available in most pharmacies), which will alert healthcare providers in case of an emergency.
www.ahealthyme.com /topic/topic13675   (608 words)

  
 Types of Chemical Reactions
All chemical reactions involve a change in substances and a change in energy.
Chemical reactions in which energy is absorbed are endothermic.
Chemical reactions in which energy is released are exothermic.
www.usoe.k12.ut.us /curr/science/sciber00/8th/matter/sciber/chemtype.htm   (525 words)

  
 Reaction Mechanisms   (Site not responding. Last check: 2007-11-06)
A reaction mechanism is a description of the path, or sequence of steps, by which a reaction occurs.
in the reaction above is much slower than that of Step 2, so the rate of the overall reaction is that of the first step.
At high temperatures, the reaction is actually single step and is first order in NO and CO.
www.chem.vt.edu /RVGS/ACT/notes/rxn_mechanisms.html   (216 words)

  
 D-T Fusion Overview
Unlike the majority of the fusion reactions that power the sun, like fusion of hydrogen with hydrogen and deuterium with deuterium, a quantum-mechanical quirk called tunneling allows deuterium and tritium to fuse together at a much larger separation distance than most fusion reactions.
With 400,000-eV deuterium ions, this D-T fusion reaction occurs six-trillion times per second in the basement of Etcheverry Hall, when the Rotating Target Neutron Source (RTNS) is operating.
Fusion reactions in turn create high-velocity alpha particles, which stop and deposit their kinetic energy, heating the surrounding plasma.
www.nuc.berkeley.edu /thyd/icf/DT_fusion.html   (1043 words)

  
 Science of Baseball: Fastball Reaction Time   (Site not responding. Last check: 2007-11-06)
Fastball Reaction Time imitates a 90-mph fastball thrown by a major league pitcher.
Although it takes some time for the signal to travel along each nerve, the major delay in your reaction time occurs at the junction points in between the different nerves involved, and between the nerves and the muscles at your fingers.
To learn more about reaction time, be sure to check out "Biological Baseball."
www.exploratorium.edu /baseball/reactiontime.html   (174 words)

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