Rates of Reactions

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  • Created by: Katie
  • Created on: 21-05-13 16:58
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  • Rates of reactions
    • Collision Theory
      • An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy and the correct orientation for a reaction to take place.
    • Activation energy
      • The minimum amount of energy needed to start a reaction.
    • The affect of concentration
      • As you increase the concentrationthe rate is quicker.
      • Higher concentration= particles closer together
      • It also increases the frequency of collisions so the rate of a reaction increases.
      • The graph would like somehing like: the line startig half way up the y axis and then going in a steady diagonal line up.
      • Real life example - in limestone when the statues are damages by acid rain. The higher the concentrationof acid in the rain water, the quicker the damage occurs.
      • Increasing the concentrationof reactants in solutions increases the frequency of collisions between particles and so it increases the rates of reactions.
    • The affect of surface area
      • The larger the  surface area, the more frequent collisions will take place, so there is a faster rate.
      • Real-life example - When you light a fire, you use small pieces of wood to begin the fire to increase the surface area. This means ther is more wood exposed to react with the oxygen.
      • The rate of a chemical reaction increases if the surface area of any solid reactant is incresed. This increases the fequency of collisions between reacting particles.
    • The affect  of temperature
      • The higher the temperature the greater the kinetic energy of the particles. Therefore, they are more likely to collide. Collisions will have more energy, causing the rate to increase.
      • Real-life example - Fridge/freezer slows down the rate of food going off.
      • Graph would look like: a stright digonal line going up from the point 0.
      • Reactions happen quicker as the temperature increases. Increasing the temperature increases the rate of the reaction because particles collide more frequently and more energetically. More of the collisions result in a reaction because a higher proportion of particles have energy greater than the activatin energy.




very helpful!!!!

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