Chemical changes

• Electrolysis is the process of splitting an ionic compound by passing electricity through it
• Electrolyte: the ionic compound that is molten or dissolved in water
• Electrode: an electrical conductor that is placed in the electrolyte and connected to the power supply
• The negative electrode is called the Cathode
• The positive electrode is called the Anode
• Oxidation is the loss of electrons and reduction is the gain of electrons.
• Uses of aluminium:

  • Pans
  • Overhead power cables
  • Aeroplanes
  • Cooking foil
  • Drink cans
  • Window and patio door frames
  • Bicycle frames and car bodies
• Displacement reaction: A more reactive metal will displace a less reactive metal from a compound
• Acid: a chemical that dissolves in water to produce H+ ions
• Base: a chemical that reacts with acids and neutralises them
• Alkali: a soluble base that produces OH- ions in a solution
• Neutralisation: when a neutral solution is formed from reacting an acid and an alkali
• Salt: a compound formed when the H in an acid is replaced wholly or partially by a metal or ammonium ion
• pH: A scale to measure acidity/alkalinity. A decrease of one pH unit is caused by a 10x increase in concentration or H+ ions
• Strong acids completely ionise in solution e.g. hydrochloric acid, nitric acid, sulphuric acid
• A weak acid is only partially ionised in solution e.g. ethanoic, citric and carbonic acids
• Potassium, sodium, lithium, calcium, magnesium and aluminium can all be extracted using electrolysis
• Zinc, iron, tin and lead can be extracted using reduction
• Copper, silver and gold can be found naturally and extracted using mining