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Topic: Exothermic reaction


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In the News (Sat 25 May 19)

  
  Exothermic reaction - an introduction - Citizendium
In chemistry, an exothermic reaction is one that releases energy in the form of heat.
It is the opposite of an endothermic reaction.
For an exothermic reaction, this gives a negative value for ΔH, since a larger value (the energy released in the reaction) is subtracted from a smaller value (the energy used for the reaction).
en.citizendium.org /wiki/Exothermic_reaction   (390 words)

  
  Lid for exothermic reaction welding mold - Patent 6776386
A lid for an exothermic reaction mold device as set forth in claim 1 wherein said exhaust vent is perpendicular to said axis of said circular opening.
A lid for an exothermic reaction mold device as set forth in claim 1 wherein said crucible is connected to a mold cavity in said block by a passageway.
Exothermic reaction welding is a known procedure for joining connectors such as, but not limited to, stranded metal cable to each other and also to ground rods and other parts.
www.freepatentsonline.com /6776386.html   (2526 words)

  
 The MSDS HyperGlossary: Exothermic and Endothermic
A reaction that is exothermic will be endothermic if run backward and vice-versa.
However, because the reaction draws heat from its surroundings, the reaction container may become cold and cause condensation or ice to form.
Therefore, it is very important to know when a chemical reaction can generate excess heat and to take appropriate measures to deal with this.
www.ilpi.com /msds/ref/exothermic.html   (544 words)

  
 Reactor for carrying out an exothermic reaction - Patent 6322755
The present invention relates to a process for carrying out an exothermic reaction in the presence of a solid catalyst in a three-phase slurry reactor which includes a slurry zone and a freeboard zone.
The exothermic reaction is a reaction which is carried out in the presence of a solid catalyst, and which is capable of being carried out in a three-phase slurry reactor.
According to a preferred embodiment of the present invention, the exothermic reaction is a Fischer-Tropsch synthesis reaction.
www.freepatentsonline.com /6322755.html   (4105 words)

  
 Exothermic reaction Summary
In chemistry, an exothermic reaction is one that releases heat.
It is the opposite of an endothermic reaction.
For an exothermic reaction, this gives a negative value for ΔH as a larger value is subtracted from a smaller value.
www.bookrags.com /Exothermic_reaction   (384 words)

  
 Media Portfolio
The forward reaction (shown in blue) is the dissociation at 25 ¡C of 1.00 mol HgO(s) into its elements and is accompanied by an increase in enthalpy of 90.83 kJ; DHÊ=Ê+90.83 kJ.
This reaction is accompanied by a decrease in enthalpy of 90.83 kJ; DHÊ=Ê-90.83 kJ.
The heat of the reaction is determined from the temperature rise in the water that surrounds the bomb.
cwx.prenhall.com /bookbind/pubbooks/hillchem3/medialib/media_portfolio/06.html   (821 words)

  
 Endothermic and Exothermic Chemical Reactions
Exothermic reactions produce heat or may even be explosive.
An example of an exothermic reaction is the mixture of sodium and chlorine to yield table salt.
Note: Technically, exothermic only refers to reactions that release heat and endothermic reactions are those that absorb heat.
chemistry.allinfoabout.com /features/endoexothermic.html   (228 words)

  
 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: )
In an exothermic reaction, the total energy absorbed in bond breaking is less than the total energy released in bond making.
For an exothermic reaction, this gives a negative value for ΔH, since a larger value (the energy released in the reaction) is subtracted from a smaller value (the energy used for the reaction).
In endergonic reactions and exergonic reactions it is the sign of the Gibbs free energy that count and not enthalpy.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Exothermic_reaction   (318 words)

  
 Chilworth Technology - Assessing Exothermic Reaction Hazards
Exothermic chemical reactions lead to explosions and flammable or toxic releases.
The key to reaction control and incident prevention is an understanding of the thermo-chemistry, obtained from laboratory tests.
A comprehensive range of instruments is available to identify and characterize reactions and to enable emergency relief systems to be designed according to the DIERS methodology.
www.chilworth.com /instrumentation_exothermic.cfm   (138 words)

  
 Endothermic and Exothermic Reactions
This reaction displays the endothermic process and illustrated the interaction between changes in enthalpy and entropy is spontaneous chemical reactions.
An endothermic reaction may thus be spontaneous at constant pressure if the positive value of the heat absorbed is offset by a sufficient increase in entropy (randomness).
In the reaction between barium hydroxide octahydrate and ammonium nitrate, the large increase in entropy is related to the increase in the number of particles present and their states (remember that two solids are combining to form a solid product and some liquid).
www.chem.umn.edu /outreach/EndoExo.html   (700 words)

  
 Exothermic and Endothermic Reactions, Calculating Energy Changes
The reaction is examined as a system and the rest of the universe makes up the surroundings.
The reaction produces or releases energy so the sign for the 213 kcal is negative, (-213 kcal).
In this reaction 43 kcal are needed to make the reaction occur.
www.800mainstreet.com /7/0007-002-exo_endothermic.html   (455 words)

  
 PASCO Chemistry Experiment - October 2002   (Site not responding. Last check: )
Students will measure the temperature change resulting from the exothermic reaction of steel wool with vinegar.
Reaction container: an empty glass peanut-butter container with a lid works well.
Identify the reaction that occurred and record it in your data table.
www.pasco.com /experiments/chemistry/october_2002   (730 words)

  
 Exothermic Reactions
Exothermic reactions are used by us all the time.
An exothermic reaction between petrol and air causes energy to be released making a car engine work.
The trick is to catch as much of the energy given out in an exothermic reaction and then put that energy to good use in a controlled way.
www.ewart.org.uk /science/patterns/pat9.htm   (361 words)

  
 Reaction Injection Molding RIM
Resistance to weathering and aging is another plus, though extended exposure to the sun’s ultraviolet rays typically results in a color shift at the surface.
When injection begins and valves in the mixhead open, the liquid reactants enter a chamber in the mixhead at pressures between 1,500 and 3,000 psi where they are intensively mixed by high-velocity impingement.
From the mix chamber, the liquid flows into the mold at approximately atmospheric pressure and undergoes an exothermic chemical reaction, forming the polyurethane polymer in the mold.
creativeurethanes.com /reactioninjectionmoldingrim.html   (408 words)

  
 HSE - Publications: CHEMICAL REACTION HAZARDS and the risk o...
The reaction vessel may be at risk from over-pressurisation due to violent boiling or rapid gas generation.
A runaway exothermic reaction can have a range of results from the boiling over of the reaction mass, to large increases in temperature and pressure that lead to an explosion.
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)

  
 191fisher_new   (Site not responding. Last check: )
This is accompanied by the growth of the polyneutron, as in reaction (1).
The reaction is exothermic and the released energy consist of gamma rays.
The Q value of the reaction, is the difference between the sum on the left and the sum on the right; in this case it is equal to -3.13 MeV.
blake.montclair.edu /~kowalskil/cf/191fisher.html   (5267 words)

  
 Mass-Energy Conservation in Reactions
In the case of endothermic reactions the addition of energy in the form of radiation is an addition of a minuscule amount of the equivalent amount of mass.
First, it is assumed that the reaction vessel is not moving at speeds approaching the speed of light, for then relativistic corrections to the mass would have to be taken into account.
All that said: your present question (about an exothermic reaction in a glass container floating in vacuum) presupposes that all of the energy generated by the exothermic reaction is lost to the environment.
www.newton.dep.anl.gov /askasci/chem03/chem03641.htm   (1829 words)

  
 Emergency Planning for Chemical Spills - Chemicals in the WorkPlace
Exothermic reactions pose special hazards whether occurring in the open environment or within a closed container.
In this case, however, increasing internal temperatures as well as the evolution of gases from the reaction may increase internal pressures to the point that the tank or container ruptures violently in an over-pressurization explosion, thus suddenly releasing large amounts of possibly flammable and/or toxic gases or vapors into the atmosphere.
Once polymerization starts, an exothermic chain reaction may occur that develops high temperatures and pressures within containers and which can lead to possible explosion or violent rupture of the container and/or discharge of flammable and/or toxic gases if safety and control systems malfunction are lacking.
www.chemicalspill.org /ChemicalsWorkPlace/reaction1.html   (3640 words)

  
 Allison Mays   (Site not responding. Last check: )
During the reaction, heat, oxygen, and water vapor are produced.
Explain that exothermic reactions are expressed in terms of DG, etc.
Objective: Have students experiment to determine which reactions are exothermic and which materials would be best to design their own heat pack.
www.bamaed.ua.edu /~amays/lessonplan1.htm   (731 words)

  
 Endo, Exothermic Reactions and Energy
Another example of an exothermic reaction is the combustion of hydrogen gas with oxygen to produce water and heat.
Another endothermic reaction is the reaction of baking soda and vinegar to make carbon dioxide and sodium acetate.
For the reaction to run backwards, all of the dye molecules would need to be in that region.
www.newton.dep.anl.gov /askasci/chem00/chem00971.htm   (1036 words)

  
 GK-12 Sensors!
An exothermic reaction produces heat, and endothermic reactions absorb heat from the surroundings.
During an exothermic reaction, more energy is produced from the formation of new bonds than energy is required to break existing bonds.
If the reaction is not dramatic enough check whether the proper amounts of chemicals were used.
www.eece.maine.edu /research/gk12/endothermicexothermicreations.htm   (210 words)

  
 EXOTHERMIC REACTION   (Site not responding. Last check: )
An EXOTHERMIC REACTION is any physical or chemical change, such as cumbustion, in which energy is released by the reactants and passed into the surroundings.
An explosion is a very rapid exothermic reaction.
When sodium or potassium phosphide come in contact with water phosphine gas is released.
www.webspawner.com /users/exothermicreaction   (71 words)

  
 Rough Science . New Zealand . Ice . Hand Warmers | PBS
The effect of an endothermic chemical reaction is a fall in the temperature of the reaction mixture.
Incredibly, the reaction between iron and moist air that produces rust is a very exothermic process and generates lots of heat.
This is a vigorous and highly exothermic reaction, which was used in the past to weld railway lines together.
www.pbs.org /weta/roughscience/series3/ice/handwarmers.html   (1252 words)

  
 The THT Micro Reaction Calorimeter
This new and exciting development in reaction calorimetry partners the strengths of traditional calorimeters with the ease of low volumes.
Utilising 1.5ml disposable reactors, this system gives rapid determination of both exothermic and endothermic reaction enthalpies.
Using only simple analysis and data manipulation it is easy to derive full reaction kinetics for a process from simple reactions.
www.thermalhazardtechnology.com /products/urc.htm   (214 words)

  
 ARTSEDGE: Oxidation & Combustion: Chemical Reactions in Fire
Strike a portable chemical reaction stick (strike-anywhere match) and note heat caused by the friction of the match against a surface causes the match to ignite.
Explain that the release of heat in a chemical reaction (or physical change) that exceeds the amount of heat used to start the reaction is an exothermic reaction.
Tell students that they will be focusing on exothermic reactions and exploring the factors that influence a chemical reaction.
artsedge.kennedy-center.org /content/3907   (1986 words)

  
 Synex, Inc.   (Site not responding. Last check: )
Good exothermic cleaning fluxes float the oxides to the surface and then put them through an exothermic chemical reaction to separate the trapped metal droplets in the oxide.
Rabbling an exothermic flux into the upper surface of the molten metal, causes flux to stick to the oxide particles due to its chemical affinity for hydrogen and oxides.
Next, the exothermic nature of the flux causes the heated dross to become very hot, thus releasing the aluminum droplets back into the bath.
www.synex-flux.com /DisplayPage.asp   (1122 words)

  
 endothermic and exothermic reactions   (Site not responding. Last check: )
An exothermic reaction in a Styrofoam cup will significantly raise the temperature in the cup.
Some chemical reactions evolve heat, resulting in a warming of the surroundings (Exothermic Reactions).
Davidson also does a neutralization reaction with 6 M NaOH and 6 M HCl for another exothermic reaction.
chemlearn.chem.indiana.edu /demos/Endother.htm   (388 words)

  
 Reaction rates
The x axis or horizontal axis is the extent of reaction or reaction path.
The magenta curve is the reaction pathway for an uncatalyzed reaction.
The reaction has the same heat of reaction but a much lower activation energy.
www.800mainstreet.com /7/0007-004-reac_rate2.htm   (470 words)

  
 Exothermic and Endothermic Reactions
endothermic reactions the temperature of the surroundings decreases.
An exothermic reaction gives out energy to its surroundings, resulting in a rise in temperature.
Exothermic reactions give out energy to their surroundings.
www.patana.ac.th /parents/curriculum/Chemistry/units/LR1403.html   (631 words)

  
 Crocodile Clips Lesson Activity   (Site not responding. Last check: )
In an exothermic reaction heat is given out.
An exothermic reaction is one in which heat is given out.
An example of an exothermic reaction is the displacement reaction between zinc and copper sulfate.
www.crocodile-clips.com /gpv70/LP/chemistry/LP0014/LA0014.htm   (187 words)

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