Rates and Energy 1

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  • Created by: Catherine
  • Created on: 22-04-13 20:15
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  • Rates and Energy 1
    • How fast?
      • rate of reaction measures speed of reaction
        • amount of reactant used, or amount of product produced
    • Collision Theory and Surface area
      • collision theory
        • reactions can only happen if particles collide
          • with enough energy to change into new substances
            • minimum energy needed to react is activation energy
        • factors increasing collisions and energy
          • temperature
          • concentration of solutions
          • pressure of gases
          • surface area of solids
    • Catalysts
      • change rate of chemical reactions
      • mainly used to speed up reactions
      • lower activation energy so more collisions result in reaction
      • solids used in powdered forms
        • this gives them large surface area to make them more effective
      • work only with one type of reaction
        • different catalysts needed for different reactions
    • temperature
      • increases speed of particles
      • particles will collide with more energy
        • increases rate of reaction
      • small change in temp has large effect on reaction rate
      • we refrigerate and freeze food to slow down reactions
    • concentration and pressure
      • more particles in the same volume
      • particles are closer together so collide more often
        • more particles in the same volume
      • increases pressure of gas puts more molecules in same volume
        • molecules collide more frequently
          • concentration and pressure
            • particles are closer together so collide more often
              • increases pressure of gas puts more molecules in same volume
                • molecules collide more frequently
        • Catalysts in action
          • economical because rarely need replacement
          • mainly used in industrial processes
          • some catalysts could cause harm to the envoironment
          • nanoparticles could provide efficient new catalysts
            • could further reduce energy costs
        • Exothermic and Endothermic Reactions
          • exothermic
            • transfer energy to the surroundings
              • surroundings heat up
            • e.g. combustion
              • e.g. oxidation
                • e.g. neutralisation
          • endothermic
            • take in energy from surroundings
              • surroundings cool down
                • thermal decomposition
        • reversible reactions
          • equal but opppositite energy transfers
          • exothermic in one direction and endothermic in other
            • e.g. blue copper sulfate crystals heated endothermic
              • water added is exothermic
        • Using energy transfers
          • handwarmersand self heating cans use exothermic reactions
          • medical cold packs use endothermic reactions

      Comments

      lisa linsdell

      Very detailed mind map for this topic, colour coordinated, Good test yourself facility. 

      VL16

      thanks, this will be really useful for revision :)

      Peter-Tandoh

      Very detailed and all the basic information needed can be found in the mind map.This will be very good for revision.

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