1 / 16

Rates of Reactions – Part 2

Rates of Reactions – Part 2. Factors affecting the rate of reaction. The surface area The concentration of the reactant The temperature at which the reaction is carried out The use of a catalyst The influence of light. 4. Rate of Reaction – Effect of Catalyst.

alfonso-mccarthy
Télécharger la présentation

Rates of Reactions – Part 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rates ofReactions – Part 2

  2. Factorsaffectingthe rate ofreaction • The surfacearea • The concentrationofthereactant • The temperatureatwhichthereactioniscarried out • The useof a catalyst • The influenceoflight

  3. 4. Rate ofReaction – EffectofCatalyst Hydrogen peroxidewater + oxygen Powderedmanganese IV oxide MnO2isaddedas a catalyst. The morefinelygroundupthemanganeseoxideisthefasterthereactiongoes. The massofthemanganeseoxideremainsthe same. Itis a catalyst.

  4. EffectofCatalyst The morecatalystyouusethefasterthereaction. The type ofcatalystyouuse will effectthereaction.

  5. Definition of a Catalyst A catalystis a substancethatincreasesthe rate of a chemicalreaction. The catalystremainschemicallyunchanged.

  6. Howdoes a cataystwork? • The provide a surface on whichothermoleculesoratomscanreact.

  7. Catalysts in Industry • Catalystsareveryusefulasyouonlyneed a smallamounttodramaticallychangethe rate of a reaction. • The catalystis not usedup so canbeusedagainandagain. • Used in theproductionofpolythene, painkillers, fertilizersandfabrics. • The processestomakethesecompounds, withoutcatalysts, wouldneedmuchmoreenergyandbemuchmorecostly.

  8. CatalyticConvertors • Used on carstoreducepollution. • Car exhaustsproduce CO, NO andunburnthydrocarbons. • The catalyticconvertorconvertsthesetolessharmfulproducts CO2, N2andwater. • The catalyticconvertorremovespollutingoxidesandcompletestheoxidationofunburnthydrocarbons.

  9. Catalytic Converters Rhodium andplatinum – preciousmetalsused

  10. Biological Catalysts • Living cells also producecatalysts, theseareproteinmoleculescalledenyzmes. • Characteristics; • Enzymes areproteins • Veryspecific – controlonlyonereaction • Temperature sensitive – stopworkingabove 45oC • pH sensitive – workbestat pH 7

  11. Enzymes in Industry • Biological washingpowdersuseenzymestoremovebiologicalstains(sweat, blood, food). • The enzymes break down protiensandfats. • Becausetheenzymesaretemperaturedependenttheyneed a washofnomorethan 40oC

  12. SurfaceCatalystsandCollisionTheory • Onemain type ofcatalystworksbyabsorbingthereactantmoleculesonto a solid surface. • This processofadsorptionbringsthereactingmoleculesclosertogether.

  13. Nickel CatalyzedHydrogenation • Finelydividednickelisusedas a catalysttoadd hydrogen tounsaturatedhydrocarbons.

  14. CollisionTheory • If a reactiononlyoccurswhenparticlescollidewiththesurfaceof a solid…. • Thenitfollowsthatthemoresurfaceareayouhave, themorecollisionsyouhave, thefasterthereactionis. • This also appliesif; • solutionsaremoreconcentrated • Gases aremorecompressed • Increasingthetemperatureincreasesthespeedtheparticlesaremovingagainincreasingtheprobabilityofcollision.

  15. ActivationEnergy • Not everycollisionproduces a reaction. • A certainamountofenergyneedstobepresentto break thebonds, EA • A catalystincreasesthe rate ofreactionbyreducingthe EA

  16. Activity • Page 216 • Exercise 7.4 on worksheet • Read aboutphotochemicalreactionsand do questions on page 218

More Related