Chemical Reactions
  If you add two substances together sometimes you get a 
  chemical reaction.  This is when a new substance is 
  made.
  It is very difficult to reverse the reaction and get the 
  original substances back.
  Signs that a chemical reaction has taken place include a 
  change in colour, heat being given off or bubbles of gas 
  being made.
         Adding acid to                 Fireworks                            Driving a car
         alkali
                                                                     
         Ice cream                        Boiling the kettle                frying an egg
         melting
                   x                      x                             
          Burning a candle              Melting                          Dissolving sugar 
                       Discuss in pairs which of these are 
                                        candle wax                       in tea
                          The changes that are not chemical 
                      chemical reactions                                  x
                                          x
                          changes are called physical changes
          Lighting a match
                                        Making                             Ironing 
                                       ice cubes                          clothes
                                          x                             x
           Printing                       Baking a cake                 Launching 
                                                                        a space 
                                                                        rocket
            x                                                               
                    Objectives
     Define and give general equations for 
       synthesis, decomposition, single-
       replacement, and double-replacement 
       reactions.
     Classify a reaction as synthesis, 
       decomposition, single-replacement, 
       single-replacement, double-
       replacement, or combustion.
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                    Objectives
     List three types of synthesis reactions 
       and six types of decomposition 
       reactions.
     List four types of single-replacement 
       reactions and three types of double-
       replacement reactions.
     Predict the products of single reactions 
       given the reactants.
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                    Background
     Thousands of known chemical reactions 
       occur in various systems. Memorizing 
       the equations for so many chemical 
       reactions would be difficult. It is more 
       useful and realistic to classify reactions 
       according to various similarities and 
       regularities.
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