Rates of reaction and energy changes

    Cards (12)

    • How do you work out the rate of reaction?
      Average rate of reaction = amount of reactant used or product formed / time
    • What’s collision theory?

      The rate of a chemical reaction depends on:
      ~the collision frequency of reacting particles
      ~the energy transferred during a collision
      ~the more collisions, the higher the rate of reactions
    • What are catalysts?

      Substances that speed up chemical reactions without being used up or chemically changed in the process. It does not affect the yield
    • How do catalysts increase the rate of reactions?
      Lowering activation energy by offering an alternative pathway
    • What are an example of biological catalysts?
      Enzymes
    • What is an exothermic reaction?
      An exothermic reaction is a chemical reaction that releases heat (/energy) to its surroundings.
    • What is an endothermic reaction?

      An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a decrease in temperature.
    • How can you measure a temperature change?
      1~ put a polystyrene cup into a large beaker of cotton
      2~add a known volume of your reagent to the cup
      3~measure the initial temperature of the solution
      4~add a measured mass/volume of your second regeant and stir the reaction mixture
      5~put a lid onto to reduce energy loss via evaporation
      6~record the temperature after a set amount of time
      7~calculate temperature change
    • What is bond breaking?
      Endothermic
    • What type is bond making?
      Its exothermic
    • What does a a negative number in energy change mean?
      The reaction is exothermic
    • What does a positive energy change mean?

      its eneothermic
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