number 3

• when a metal reacts with oxygen you get a metal oxide
• what do you get when you react a metal and oxygen 


  a metal oxide
• gaining oxygen is an oxidation reaction
• what type of reaction involves gaining oxygen 


  oxidation reaction
• losing oxygen is called a reduction reaction
• what reaction involves losing oxygen

  reduction reaction
• What type of ion do metals form 


  positive ion
• metals form positive ions
• The reactivity of a metal is related to its tendency to form positive ions
• How can metals less reactive than carbon be extracted 


  reduction with carbon
• acids and metals make 


  salt and hydrogen
• solid ionic compound cannot conduct electricity
• why cant solid ionic compounds conduct electricity 


  the ions are locked in and are not free to move
• when an ionic compound is melted or dissolved in water the forces of attraction are broken and the ions are free to move
• liquids that can conduct electricity are called

  electrolytes
• why are the anode and cathode made of graphite 


  it conducts electricity

  it has a very high melting point
• why must the anode be replaced regularly 


  the oxygen molecules produced at the anode react with the graphite and form carbon dioxide gas
• aqueous solutions are dissolved in water
• at the native electrode hydrogen is produced if its less reactive than the metal
• at the positive electrode oxygen is produced unless the solution contains halide ions
• at the anode negatively charged ions lose electrons so its oxidation
• what type of reaction happens at the cathode 


  reduction
• what type of reaction happens at the anode 


  oxidation
• strong acids are completely ionised in aqueous solutions
• weak acids are partially ionised in aqueous solutions
• what can you use to measure pH

  universal indictor , pH probe
• pH probe is more accurate
• what is an acid 


  any substance that forms aqueous solutions with a pH les than 7
• acids release hydrogen ions in water
• what is a base 


  any substance with a pH greater than 7
• what are alkalis 


  a base that dissolves in water to form a solution with a pH greater than 7
• what ions do alkalis form

  hydroxide ions
• acids and bases make salt and water