chemical reactions

• metal + oxygen produces metaloxide this is an oxidation reaction
• when metals lose oxgen its a reduction reaction
• OIL RIG

  -oxidation is loss

  -reduction is gain

  of electrons
• acids

  • HCL- hydrochloric acid
  • H2SO4 - sulfuric acid
  • HNO3 - nitric acid
  • ph 0-6
  • in a aqueous solution it produces H+ ions
• bases and alkalis

  • neutralise acids to produce salt and water
  • alkalis are soluble bases
  • in an aqueous solution they produce OH- ions
  • they are metaloxides or metalhydroxides
  • ph 8-14
• test for ph

  • electronically using a Ph probe
  • universal indicator which changes colour
• acid + metals produce salt and hydrogen

  • all acids contain hydrogen
  • metal displaces hydrogen to create salt
• iron reacts slowly with dilute acids and water
• zinc reacts quite rapidly with dilute acids and water
• magnesium reacts rapidly
• strong acids

  • fully ionise in aqueous solutions
  • HCL
  • H2SO4
  • HNO3
• weak acid

  • have a reversible arrow
  • only partially ionise in aqueous solutions
  • carbonic acid
  • ethanoic acid
  • citric acid
• as the Ph decreases by one unit the concentration of H+ ions increase 10 times
• electrolysis is used to extract metals that cant be displaced by carbon
• aluminium oxide

  • has a very high melting point (2000)
  • cryolite is added to make the mixture impure and lower the melting point
  • low density used for plans parts and cans
• aluminium oxide

  1. $Al^{3+}$ ions
  2. $O^{2-}$ ions
• at the cathode (negative electrode) aluminium ions gain 3 electrons and forms aluminium
• electrodes:

  • made of graphene
  • high melting pointing point
  • electrical conductor
  • needs to be replaces regularly
  • oxygen reacts with the carbon and produces carbondioxide
• in an aqeuous solution at the cathode hydrogen is produced if the metal is more reactive ( anything above copper and silver)
• in an aqueous solution at the anode oxygen is formed unless a halide ion is present
• electrodes should be inert (unreactive) so platinum is used
• half equations at the anode when oxygen is formed:

  
  

  $4OH^-\ \rightarrow\ O_2\ +$$\ 2\ H_2O\ +$$4e^-$
• in an aqueous solution at the anode (positive electrode) oxygen loses two electrons
• half equations at the cathode for aluminium

  
  

  $Al^{3+}+$$\ 3e^-\ \ \rightarrow\ Al$
• exctract metals from metaloxides using displacement reactions using carbon because its cheap
• in an aqeuous solution water ionises into H+ and OH -ion
• acid + metal carbonate produces salt + water + carbondioxide
• half equation at the anode ( oygen )

  
  

  $2O^{2-}\ \rightarrow\ O_2\ +$$\ 4e^-$