CHEMICAL REACTIONS

• What is an endothermic reaction?

  a reaction that takes in energy from its surroundings
• what is an exothermic reaction?

  A reaction where energy is released to the surroundings.
• What does precipitate mean?

  When insoluble solid is formed inside a solution
• what does effervescence mean?

  bubbles, fizz
• What is a chemical change?

  When ONE new substances are made
• What is a physical change?


  When NO new substances are made
• Which side of an equation is the reactants?

  left

  
• Which side of an equation are the products?

  right

  
• What is the conservation of mass?

  during a reaction atoms are neither destroyed nor created. Just REARANGED.

  Total mass of reactants EQUAL the total mass of the products
• Odourless meaning


  A substance with no smell
• Oxidation meaning


  A reaction where a substance reacts with oxygen
• Combustion meaning


  the process of burning something
• Reduction meaning


  A reaction where oxygen is removed from a substance
• Electrolysis meaning


  A process by which an electric current breaks chemical bonds.
• Displacement reaction meaning


  A more reactive metal will displace a less reactive metal
• Neutralisation reaction


  acid + base = salt + water.

  When acids and alkalis react together they will NEUTRALISE each other.
• What happens to a substance when it is burned?

  Substance becomes heavier
• When does a substances stop burning?


  When one of the key elements for a fire are reduced

  
• Why do substances get heavier when burned?

  the oxygen atoms from the air add to the starting material in the reaction.