C7-rates of reaction and energy changes

• For a reaction to occur, there must be successful collisions between particles
• Increasing rate of reaction in terms of collisions

  Increase the frequency and/or energy of collisions
• Increase temperature


  Rate of reaction increases
• Increase surface area

  Rate of reaction increases
• Increasing surface area of a solid

  Break it into smaller pieces
• Increase concentration


  Rate of reaction increases
• Increase pressure


  Rate of reaction increases
• Factors that can affect rate of reaction

  • Temperature
  • Concentration (solutions)
  • Surface area (solids)
  • Pressure (gases)
• Rate of reaction starts off quickly and gradually slows down as the reactants get used up and so the frequency of successful collisions decreases
• Catalyst

  A substance that speeds up the rate of a reaction without altering the products of the reaction, being itself unchanged chemically and in mass at the end of the reaction
• Adding a catalyst

  Increases rate of reaction
• How a catalyst increases rate of reaction

  It lowers the activation energy so the frequency of successful collisions increases
• Biological catalysts

  Enzymes, can be used in the production of alcoholic drinks