Chemistry equations

• Equations for AQA Chemistry

  • The mole (HT)
  • Avogadro's number (HT)
  • Concentration in g/dm³
  • Concentration in mol/dm³ (HT)
  • Gas Volumes (HT)
  • Percentage Yield (HT)
  • Atom Economy
  • Calculating energy changes (HT)
  • Rate of reaction
  • Chromatography
• Common Reactions you should be familiar with

  • Combustion of carbon
  • Combustion of hydrogen
  • Combustion of hydrocarbons
  • Oxidation of metals
  • Reaction of metals with water
  • Displacement of halogens
  • Reaction of metal with acid
  • Reaction of metal oxide with acid
  • Displacement of metals
  • Ionic equation for displacement (HT)
  • Neutralisation
  • Ionic equation for neutralisation (HT)
  • Marble chips (calcium carbonate) and acid
  • Electrolysis of molten ionic compounds
  • Cracking
  • Energy changes - reaction profile diagrams
  • Electrolysis of aqueous ionic compounds (sodium chloride)
  • Half equations for electrolysis (HT)
  • Bromine test for alkenes
  • The Haber process
• moles


  mass / Mr (relative atomic mass)
• Avogadro's number


  There are 6.02 x 10²³ particles of a substance in 1 mole
• Concentration in g/dm³


  concentration = mass (g) / volume (dm³)
• Concentration in mol/dm³ (HT)


  • concentration = moles (mol) / volume (dm³)
  • moles = concentration x volume (in dm³)
• Gas Volumes (HT)


  • 1 mole of any gas has a volume of 24dm³
  • volume (dm³) = moles x 24dm³
• Converting from cm³ to dm³

  1dm³ = 1000cm³
• Percentage Yield (HT)


  Mass of product actually made / Maximum theoretical mass of product x 100
• Atom Economy


  Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation x 100
• Calculating energy changes (HT)

  Energy change in a reaction = Total energy needed to break the bonds in reactants - Total energy released when bonds in the products are formed
• Rate of reaction


  • mean rate of reaction = quantity of reactant used / time taken
  • mean rate of reaction = quantity of product formed / time taken
• Chromatography


  Rf = distance moved by substance / distance moved by solvent
• This list should help you to identify most the reactions that you will be expected to know about for the examination
• This is not an exhaustive list, for example I have used examples of metals or acids which may be substituted for other metals or acids
• Combustion of carbon


  Carbon + Oxygen → Carbon dioxide
• Combustion of hydrogen


  Hydrogen + Oxygen → Water
• Combustion of hydrocarbons


  Methane + Oxygen → Carbon dioxide + Water
• Oxidation of metals


  Copper + Oxygen → Copper (II) oxide
• Reaction of metals with water

  Sodium + Water → Sodium hydroxide + Hydrogen
• Displacement of halogens


  Sodium bromide + Chlorine → Bromine + Sodium chloride
• Reaction of metal with acid

  Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen
• Reaction of metal oxide with acid

  Copper (II) oxide + Hydrochloric acid → Copper (II) chloride + Water
• Displacement of metals


  Copper (II) sulfate + Magnesium → Magnesium sulfate + Copper
• Ionic equation for displacement (HT)


  Cu2+

  (aq) + Mg(s) → Mg2+

  (aq) + Cu(s)
• Neutralisation


  Sodium hydroxide + Hydrochloric acid → Sodium chloride + Water
• Ionic equation for neutralisation (HT)

  H+

  (aq) + OH-

  (aq) → H2O(l)
• Marble chips (calcium carbonate) and acid


  Calcium carbonate + Hydrochloric acid → Calcium chloride + Water + Carbon dioxide
• Electrolysis of molten ionic compounds

  Lead bromide → (Molten) lead + Bromine (gas)
• Cracking


  Decane → Pentene + Pentane
• Energy changes - reaction profile diagrams
• Electrolysis of aqueous ionic compounds (sodium chloride)

  Sodium chloride + Water → Sodium hydroxide + Hydrogen + Chlorine
• Half equations for electrolysis (HT)

  Cathode: 2H+

  (aq) + 2e- → H2(g)

  Anode: 2Cl-

  (aq) → Cl2(g) + 2e-
• Bromine test for alkenes

  Ethene + Bromine → Dibromoethane
• The Haber process


  Nitrogen + Hydrogen → Ammonia