Chemical Changes

• what is the reactivity series

  • a league table for metabls
  • more reactive metals at the top
  • less reactive near the bottom
  • a more reactive metal displaces a less reactive metal
• what is the order of the reactivity series

  Pretty ------------------> potassium

  Songs ------------------> sodium

  Can ------------------> calcium

  Make ------------------> magnesium

  A ------------------> aluminium

  Cunt ------------------> carbon

  Zelous ------------------> zinc

  In ------------------> iron

  The ------------------> tin

  Loving ------------------> lead

  Heart ------------------> hydrogen

  Cus ------------------> copper

  Shes ------------------> silver

  Gold ------------------> gold
• what is formed when metals react with water

  they produce a metal hydroxide + hydrogen

  • lithium + water -> lithium hydroxide + hydrogen
  • the more reactive a metal, the faster the reaction
• what is formed when metals react with dilute acide

  they produce a salt + hydrogen

  • sodium + hydrochloric acid -> sodium chloride + hydrogen
  • metals below hydrogen in the reactivity series (copper + silver + gold) do not react with dilute acids
• what is the general formula for a reaction between an acid and a metal

  acid + metal -> salt + hydrogen

  • hydrochloric acid + sodium -> sodium chloride + hydrogen
• what is the general formula for the reaction between acids and alkali

  acid + alkali -> salt + water

  • hydrochloric acid + sodium hydroxide -> sodium chloride + water
• how are salts name

  1.) the first part comes from the metal in the metal carbonate / oxide / hydroxide

  • e.g. sodium

  2.) the second part comes from the acid that was used to make it

  • e.g. hydrochloric acid -> chloride
• what is a redox reaction

  • when a metal react with acids, a redox reaction occurs
  • a redox reaction occurs when both oxidation + reduction take place at the same time

  e.g - 2H+ + Ca -> Ca2+ + H2

  • this ionic equation can be further split into 2 half equations
  • Ca -> Ca2+ + 2e- <- oxidation is the loss of electrons
  • 2H+ + 2e- -> H2 <- reduction is the gaining of electrons
• how does the pH scale affect chemical change

  • in aqueous solutions acids ( red side -> 1-6) produce H+ ions + alkali (purple side -> 8-14) produce OH- ions
  • neutral solutions are pH7 (green)

  e.gn neutralisation in water

  • hydrogen ions form an acid to react with hydroxide ions that form an alkali
  • this produces water
  • H+ + OH- -> H2O
• what is the general formula for a reaction between an acid and a metal oxide


  acid + metal oxide -> salt + water

  • sulfuric acid + copper oxide -> copper sulfate + water
• what is the general formula for a reaction between an acid and a carbonate

  acid + carbonate -> salt + water + carbon dioxide

  • hydrochloric acid + calcium carbonate -> calcium chloride + water + carbon dioxide
• how do you make a soluble salt

  • make a saturated solution by stirring copper oxide into sulfuric acid until fully dissolved
  • filter the solution to remove excess copper oxide solid
  • half fill a beaker with water + set this over a bunsen burner to heat the water
  • place an evaporating dish on top of the beaker + add some of the solution to the basin
  • heat it until crystals begin to form
  • once cooled pour the remaining liquid into a crystallising dish + leave to cool for 24 hours
  • remove the crystals with a spatula + pat it dry between paper towels
• what do strong acids do

  • they completely dissociate in a solution

  HCL -> H+ + Cl-

  • hydrochloric acid is able to completely dissociate in solution to form hydrogen + chloride ions
• what do weak acids do

  • they only partially dissociate in a solution

  CH3COOH -> CH3COO- + H+

  • acetic acid only partially dissociates to form hydrogen + acetate ions
  • should have double arrow to show it is a reversable reaction
• what is electrolysis

  • the splitting of an ionic substance using electricity
• how do you set up an electrical circuit for electrolysis

  • 2 electrodes should be placed in the electrolyte
  • the electrodes are conducting rods -> one rod connects to the positive terminal + the other rod connects to the negative terminal
  • the electrodes are inert (do not react in this reaction and are often made from graphite or platinum
• what attracts during electrolysis

  opposites attract

  • positively charged ions are attracted to the negative electrode
  • negatively charged ions are attracted to the positive electrode
  • when ions reach the electrode they lose their charge + become elements

  (positive electrode) -> anode + negative ions

  (negative electrode) -> cathode + positive ions
• what happens during the electrolysis of aqueous solutions

  • gases may be given off or metals deposited at the electrode, depending on the elements reactivity
  • if a metal is more reactive (not gold + silver + copper) -> hydrogen is produced at the cathode + the anode ions lose electrons
  • this is called oxidation
• how are metals extracted through electrolysis

  • this only occurs if the metal reacts with carbon or if it is too reactive to be extracted by reduction with carbon
  • lots of energy is used to melt the compounds containing metals
  • aluminium is manufactured using electrolysis
  • aluminium oxide has a high melting point so it would be expensive + not energy efficient to melt
  • instead molten cryolite is added to aluminium oxide to lower the melting point
• what does OIL RIG stand for

  Oxidation Is Loss of electrons

  Reduction Is Gaining of electrons
• what are the steps to electrolysis of molten ionic compound

  • when an ionic compound is melted the ions become free to move + conduct electricity
  • two electrodes are placed in the molten compound
  • a voltage is applied across the electrodes and + ions attract to the cathode and - attract to the annode
  • positive ions at the cathode gain electrons + become neutral atoms or molecules
  • negative ions at the anode lose electrons + form neutral atoms or molecules
  • the atoms then bond to form a covalent molecule