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  • Created on: 28-03-13 13:49
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    • Collision Theory
      • More collisions increase the rate of reaction.
        • Higher the concentration increases the collisions
        • Higher the temperature increases the collisions
    • Energy transfer in reactions.
      • Exothermic reactions let heat out, an exothermic reaction is one where it transfers energy to the surroundings, usually in a form of heat or rise in temperature,
        • an example would be combustion burning of fuels.
          • Acids and Alkalis are on the PH scale from 0-14 The strogest acid is PH 0 and the straongest Alkalis is PH 14
            • Number 7 is neutral
          • Acids and Alkalis
        • In  Endothermic reactions heat is taken in. An endothermic reaction is one which takes in energy from surroundings, usually a form of heat or a fall in temperature.
          • Reversible reactions can be either endothermic or Exothermic
    • Measuring the rate of reaction.
      • The formula is the rate of reaction= the amount of reactant used or amount of product formed over Time.
        • Change in Mass
        • Precipitation
        • The volume of gas given off.
        • The rate of reaction can be observed either by measuring how quickly the reactants are used up or how quickly the products are formed.
    • Rate of reaction experiments
      • 1) Reaction of Hydrochloric Acid and Marble chips.
      • 2) Reaction of Magnesium Metal with Dilute HCL
      • 3) Sodium Thiosulfate and HCL produce a Cloudy precipitate.
      • 4) The decomposition of Hydrogen Peroxide.
    • Reactions can go at all sorts of different rates.
      • 1)  one of the slowest is the rusting of Iron.
      • A Moderate Speed reaction is a metal like magnesium reacting with acid to produce a gentle steam of bubbles.
      • A really fast reaction is an explosion where it's all over in a matter of seconds.
    • Electrolysis
      • Means the "splitting up of electricity".
      • If you pass an electric current through an ionic substance that's molten or in solution, it breaks down the elements it's made of This is called ELECTROLYSIS
        • It requires a liquid to conduct the electricity, called an electrolyte.
        • In either case it's free ions which conduct the electricity, and allow the whole thing to work.
          • For an electrical circuit to be complete, there's got to be a flow of electrons. Electrons are taken away from the ions at the positive electrode and given to the other ions at the negative electrode. As ions gain or lose electrons they become atoms or molecules and are released.
      • Electrolytes contain free ions they're usually the molten or dissolved ionic substance.
  • faster the collisions increase the rate of reaction
    • larger the surface area  increases the collisions
  • Catalysts speed up reactions they are substances which speed up reactions without being changed or used up.
    • Catalyst help reduce costs in industrial reactions


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