C3.3 and C3.4 (types of chemical reactions+electrolysis)

• what is a redox reaction?

  a reaction where reduction and oxidation happen at the same time
• what is reduction in terms of transfer of oxygen?

  reduction is the loss of oxygen from a substance
• what is oxidation in terms of transfer of oxygen?

  Oxidation is the gain of oxygen by a substance
• what happens when aluminium gains oxygen?


  It is oxidised to aluminium oxide
• What happens when iron oxide loses oxygen?

  it is reduced to iron
• what is a reducing agent?

  The agent that reduces a substance originally with oxygen to end up without oxygen
• what is an oxidising agent?

  an agent that oxidises a substance originally without oxygen to end up with oxygen
• what does oil rig stand for?

  Oxidation is loss of electrons, reduction is gain of electrons
• what does a half equation show?

  The change that happens to one reactant in a reaction
• what is reduction in terms of electrons?

  Gain of electrons
• what is oxidation in terms of electrons?

  loss of electrons
• what is an acid?

  A substance that releases hydrogen ions when it dissolves in water to make an aqueous solution
• what makes a solution acidic?

  Hydrogen ions
• what is a base?

  Usually a metal oxide or metal hydroxide that can neutralise acids
• what can also be the name of a base that can dissolve in water?


  could also be an alkali
• what does an alkali release when dissolved in water?

  Hydroxide ions
• what does it mean if the pH is less than 7?


  Acidic
• what does it mean if the pH is equal to 7?


  Neutral
• what does it mean if the pH is more than 7?


  Alkaline
• how do you work out the pH of a solution?


  Using universal indicator or a pH meter
• What colour normally represents acidic?


  Red
• what colour normally means neutral?


  green
• what colour normally means alkaline?


  Blue
• what is neutralisation?


  The reaction between an acid and a base or an alkali to form a salt and water
• what is the equation for an acid + a base?


  Acid + base --> salt + water
• what happens to the pH when a base or alkali is added to and acid?


  Increases
• what happens to the pH if an acid is added to a base or an alkali?


  Decreases
• how can you predict the salt made in a neutralisation reaction?


  The first part comes from the metal in the base or in the alkali

  The second part comes from the acid used
• what happens when an acidic solution and an alkaline solution react together?

  It produces water

  The ionic equation is H+ + OH- -> H2O
• what are carbonates?


  Ionic compounds that contain the carbonate ion CO3 2-
• what do carbonates reacting with acids form?


  Salt, water, and carbon dioxide
• true or false = most carbonates are insoluble in water

  True
• what carbonates are soluble in water?

  Group 1 carbonates, sodium carbonate and ammonium carbonate
• what does an acid + metal make?


  Salt + hydrogen
• what does a dilute acid mean?


  It contains a low ratio of acid to volume of solution
• what does a concentrated acid mean?


  Contains a high ratio of acid to volume of solution
• what happens when acids release hydrogen ions?


  A covalent bond in the acid molecule breaks, producing a hydrogen ion (H+) and a negatively charged ion
• what are weak acids in terms of ions?


  Only partially ionised which means that only a small amount of their molecules release H+ ions
• what are strong acids in terms of ions?

  Fully ionised, all of their molecules release H+ ions
• what sometimes happens to weak acids?


  Their reaction does not go to completion and 2 arrows in opposite directions are shown in the equation