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Topic: Chemical reaction


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  Chemical Reaction - MSN Encarta
A chemical reaction is a process that always results in the interconversion of chemical substances.
Chemical Reaction, process by which atoms or groups of atoms are redistributed, resulting in a change in the molecular composition of substances.
An example of a chemical reaction is formation of rust (iron oxide), which is produced when oxygen in the air reacts with iron.
encarta.msn.com /encyclopedia_761573235/Chemical_Reaction.html   (1545 words)

  
 CHEMICAL REACTION,
Chemical symbols and formulas are employed to describe chemical reactions; they denote substances having one set of formulas changing into substances having another set of formulas.
One kind of reaction, ion matching, is easy to understand as due to the pairing (or dissociation) of ions to form (or dissociate) neutral ionic substances, where a double arrow (instead of an equal sign) emphasizes the two possible directions of reaction.
Common examples of redox reactions involving oxygen are the rusting of metals such as iron (in which case the metals are oxidized by atmospheric oxygen), combustion, and the metabolic reactions associated with respiration.
www.history.com /encyclopedia.do?vendorId=FWNE.fw..ch111300.a.b10.c40   (4617 words)

  
 Education Resources » Chemical reaction
Classically, chemical reactions encompass changes that strictly involve the motion of electrons in the forming and breaking of chemical bonds, 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.
Chemical reactions may be classified in different ways depending on the particular aspect considered for elaborating the division, or on the branch of Chemistry which the classification originates from.
Reaction rates are related to the concentrations of substances involved in reactions, as quantified by the law of mass action.
www.thecatalyst.org /resource/2006/04/21/Chemical-reaction   (1554 words)

  
 Chemical Equations
A chemical equation is the shorthand that scientists use to describe a chemical reaction.
During this reaction, chemical bonds break and re-form and the products that are produced are carbon dioxide and water vapor (and, of course, light and heat that you see as the flame).
To balance the chemical equation we must add the coefficient "2" in front of the oxygen molecule on the left side of the equation, showing that two oxygen molecules are consumed for every one methane molecule that burns.
www.visionlearning.com /library/module_viewer.php?mid=56   (1161 words)

  
 chemical reaction. The Columbia Encyclopedia, Sixth Edition. 2001-07
Chemical reactions are classified according to the kind of change that takes place.
In so-called replacement reactions the place of one of the elements in a compound is taken by another element reacting with the compound.
The rates at which chemical reactions proceed depend upon various factors, e.g., upon temperature, pressure, and the concentration of the substances involved and, sometimes, upon the use of a chemical called a catalyst.
www.bartleby.com /65/ch/chem-re.html   (381 words)

  
 Chemical Reactions
The reaction of two or more elements together results in the formation of a chemical bond between atoms and the formation of a chemical compound.  But why do chemicals react together?  The reason has to do with the participating atoms' electron configurations.
Reactions that proceed immediately when two substances are mixed together (such as the reaction of sodium with chlorine or urea with ammonium chloride) are called spontaneous reactions.
In the case of the match, you supply activation energy in the form of heat by striking the match on the matchbook; after the activation energy is absorbed and the reaction begins, the reaction continues until you either extinguish the flame or you run out of material to react.
www.visionlearning.com /library/module_viewer.php?mid=54   (922 words)

  
 CHEMTUTOR REACTIONS
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.
Chemical equations are written with the symbols of materials to include elements, ionic or covalent compounds, aqueous solutions, ions, or particles.
Chemical reactions, also called chemical changes, are not limited to happening in a chemistry lab.
www.chemtutor.com /react.htm   (3274 words)

  
 CHEMICAL KINETICS
Observe that use of the stoichiometric coefficient insures that the rate of a chemical reaction is the same regardless of which chemical species is used in the definition.
The rate law is an expression for the reaction rate in terms of concentrations of chemical species involved in the reaction.
In the collision theory of bi-molecular gas phase reactions, the frequency factor A is interpreted as the frequency of encounters among reactants irrespective of energy.
www.chem.hope.edu /~polik/Chem345-1997/kinetics/ChemicalKinetics1.html   (1138 words)

  
 ACM contest and Blackout
Whenever two chemicals are mixed, some heat is generated and released into the air and the mixed chemical is a known chemical of possibly other type than the original two.
Since the chemist lacks funding to buy necessary equipments to protect himself from the heat generated, it is utmost important to find a way to mix all the chemicals together that produces the least total heat, regardless of the final chemical type.
However, if the chemicals are mixed in the (2 (1 (2 3))) order, it will produce (-500)+0+(-10)= -510 units of heat, which is also the least total heat possible.
acm.uva.es /p/v106/10604.html   (415 words)

  
  Chemical Reaction Lesson Plans
Chemical Changes- The second grade students will investigate some chemical changes and reactions and should be able to identify at least four characteristics that indicate a chemical change.
Chemical Changes- To learn that the formation of gas bubbles is an indication of a chemical change.
Chemical Reaction Rates- To learn phenomenologically some of the factors which affect the rates of chemical reactions.
www.teach-nology.com /teachers/lesson_plans/science/chemistry/reactions   (1275 words)

  
 Online Encyclopedia and Dictionary - Chemical reaction   (Site not responding. Last check: )
A chemical reaction or is a reaction of two or more chemicals (reagents), yielding a chemical change and a product(s).
A chemical change is defined as molecules attaching to each other to form larger molecules, molecules breaking apart to form two or more smaller molecules, or rearrangement of atoms within molecules.
In a rearrangement reaction, the atoms and bonds within a molecule rearrange to form an isomer of the original compound.
fact-archive.com /encyclopedia/Chemical_reaction   (827 words)

  
 Learn more about Chemical reaction in the online encyclopedia.   (Site not responding. Last check: )
Decomposition is the opposite of synthesis, and in this type reaction individual atoms are no longer bonded.
In single displacement reactions, one of the atoms' formula is exchanged with another one's.
In double displacement reactions, both reactants' bonded atoms are exchanged.
www.onlineencyclopedia.org /c/ch/chemical_reaction.html   (481 words)

  
 Chemical Reaction Equations
Because chemical bonds are broken and new bonds are formed, the phase transition of diamond and graphite is a chemical reaction.
Chemicals or substances change converting to one or more other substances, and these changes are called chemical reactions.
Chemical reactions are often accompanied by the appearance of gas, fire, precipitate, color, light, sound, or odor.
www.science.uwaterloo.ca /~cchieh/cact/c120/reaction.html   (1717 words)

  
 Chemistry - Chemical reaction
A chemical reaction or is a reaction of two or more chemicals (reagents), yielding a chemical change and a product(s).
A chemical change is defined as molecules attaching to each other to form larger molecules, molecules breaking apart to form two or more smaller molecules, or rearrangement of atoms within molecules.
Chemical equilibrium is the state in which the forward and reverse reaction rates are equal, thus preserving the amount of reactants and products.
www.chemistrydaily.com /chemistry/Chemical_reactions   (818 words)

  
 A Checklist for Inherently Safer Chemical Reaction
The chemical substances in the process might not be considered to be reactive chemicals, but this does not mean that the process does not have reactivity hazards.
If the maximum adiabatic reaction temperature exceeds the reaction mixture boiling point, the reaction is capable of generating pressure in a closed vessel and you will have to evaluate safeguards to prevent uncontrolled reaction and consider the need for emergency pressure relief systems.
For exothermic reactions, the temperature may also be higher near the point of introduction of reactants because of poor mixing and localized reaction at the point of reactant contact.
home.att.net /~d.c.hendershot/papers/ccps10-02.htm   (2888 words)

  
 HSE - Publications: CHEMICAL REACTION HAZARDS and the risk o...
Such a chemical process often releases energy, in the form of heat, and the reaction is described as exothermic.
In order to deal with chemical reaction hazards first you need to identify them, then to decide how likely they are to occur and how serious their consequences would be.
The basis of safety for a chemical reaction is the combination of measures which are relied upon to ensure safe operation.
www.hse.gov.uk /pubns/indg254.htm   (2150 words)

  
 SparkNotes: Reaction Mechanisms: Mechanisms of Chemical Reactions
Understanding the meaning of the reaction coordinate is not important, just know that small values of reaction coordinate (0-0.2) mean little reaction has taken place and large values (0.8-1.0) mean that the reaction is almost over.
E on the diagram, determines whether the reaction is exothermic or endothermic.
Let's consider chemical reactions more deeply to derive an equation which describes the relationship between the rate constant of a reaction and its activation barrier.
www.sparknotes.com /chemistry/kinetics/mechanisms/section1.html   (1671 words)

  
 Chemical Kinetics: Rate of Reaction
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.
Determine the stoichiometric coefficients for a chemical reaction.
www.chm.davidson.edu /ChemistryApplets/kinetics/RateOfReaction.html   (403 words)

  
 chemical reaction — FactMonster.com
chemical reaction, process by which one or more substances may be transformed into one or more new substances.
The rates at which chemical reactions proceed depend upon various factors, e.g., upon temperature, pressure, and the concentration of the substances involved and, sometimes, upon the use of a chemical called a
The Chemistry of Biology: Chemical Reactions: Ionic, Covalent, and Polar Covalent Bonds - The Chemistry of Biology Chemical Reactions: Ionic, Covalent, and Polar Covalent Bonds The...
www.factmonster.com /ce6/sci/A0811636.html   (419 words)

  
 Ca to Cl
A concept related to rate of reaction, particularly applicable to the progress in one direction only of component reaction steps in a complex system or to the progress in one direction of reactions in a system at dynamic equilibrium (in which there are no observable concentration changes with time).
Detectable chemical reactions normally involve sets of molecular entities, as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e.
If the equilibrium mixture of a chemical reaction is disturbed by a sudden change, especially of some external parameter (such as temperature, pressure, or electrical field strength), the system will readjust itself to a new position of the chemical equilibrium or return to the original position, if the perturbation is temporary.
www.chem.qmul.ac.uk /iupac/gtpoc/CaCl.html   (2316 words)

  
 :: MIT ChE :: Research - Catalysis and Chemical Reaction Engineering
A simple chemical reaction - the rearrangement of electrons and bonding partners - occurs between two small molecules.
From understanding the kinetics of the reaction, and the equilibrium extent to which it can proceed, come applications: the network of reactions during combustion, the chain reactions that form polymers, the multiple steps in the synthesis of a complex pharmaceutical molecule, the specialized reactions of proteins and metabolism.
Chemical kinetics is the chemical engineer's tool for understanding chemical change.
web.mit.edu /cheme/research/catalysis.html   (346 words)

  
 Chemical Reactions
A chemical reaction is the pathway by which two substances bond together.
To write the chemical reaction you would place the reactants (the substances reacting) on the left with an arrow pointing to the the products (the substances being formed).
To write a chemical reaction correctly, the number of atoms on the left side of a chemical equation has to be precisely balanced with the atoms on the right side of the equation.
web.jjay.cuny.edu /~acarpi/NSC/6-react.htm   (1009 words)

  
 Types of Chemical Reactions
Chemical changes are a result of chemical reactions.
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)

  
 CHEM: Chemical Reaction Engineering
Knowledge of the advantages and drawbacks of chemical reactor properties is therefore essential for all chemical and biochemical processes.
Research in chemical reaction engineering includes the kinetics and dynamics of chemical and biochemical processes coupled with molecular mass transport phenomena.
Other important research fields are turbulence modelling linked to chemical reaction, fermentation processes, catalyst deactivation, process control, stability and optimisation.
www.chalmers.se /chem/EN/divisions/chemical-reaction   (160 words)

  
 Three Share Nobel for Chemical Reaction Work - New York Times
Three scientists share this year's Nobel Prize Chemistry for developing a chemical reaction that swaps out pieces of molecules in a swing-your-partner-around square dance manner, it was announced today.
The chemical reaction, developed over the last 35 years, enables a more efficient and more environmentally friendly way to manufacture of plastics, drugs and other materials.
The winners are Yves Chauvin, 74, who retired a decade ago from the French Petroleum Institute in Rueil-Malmaison, France; Robert H. Grubbs, 63, a professor of chemistry at the California Institute of Technology; and Richard R. Schrock, 60, a professor of chemistry at the Massachusetts Institute of Technology.
www.nytimes.com /2005/10/05/science/05cnd-nobel.html?ex=1286164800&en=d3b5ccaf33369e0f&ei=5090&partner=rssuserland&emc=rss   (785 words)

  
 Chemical Reaction
Chemical firms across Europe and beyond are having to come to terms with Reach, the European Union's recently introduced environmental legislation.
Several big chemical deals are in that pipeline, including Sabic-GE Plastics, Basell-Lyondell, Hexion-Huntsman, and Carlyle-PQ Corp. Industry deals with committed financing are likely to proceed, say MandA advisers that CW contacted earlier this month.
Three officials of Abiquim (São Paulo), the Brazilian chemical industry association, were among those killed in yesterday’s crash of a TAM Airlines flight in São Paulo, according to a post on Abiquim’s Web site (www.abiquim.org.br).
chemicalweek.blogspot.com   (1957 words)

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