8.1 EXOTHERMIC REACTIONS

• Burning

  a chemical reaction where a substance (called a fuel) combines with oxygen.
• Fuels


  have a store of chemical energy eg. charcoal, wood, coal, natural gas and oil. when burnt, chemical energy -> thermal, light and sound energy which disspate (spread out) into the surroundings.
• Combustion


  another word for burning. a chemical reaction in which thermal energy is given out = exothermic reaction.
• Hydrogen

  • can be used as fuel in a model rocket
  • combustion of it is an exothermic reaction
  • hydrogen and oxygen combine to form water
  • chemical energy is release and changed into kinetic, thermal, sound and light energy
• Oxidation Reaction


  When a substance burns, it combines with oxygen to form an oxide
• With Acid


  magnesium added to dilute hydrochloric acid warms the test tube up, resulting in an exothermic reaction.
• With Water

  • combined with potassium, the bonds between the atoms of oxygen and hydrogen break
  • atoms rearrange to form the products hydroxide and hydrogen
  • stored chemical energy -> thermal energy, which dissipates into the environment