4. chemical changes

• Reactivity Series of Metals

  • Potassium
  • Sodium
  • Calcium
  • Magnesium
  • Aluminium
  • Zinc
  • Iron
  • Tin
  • Lead
  • Copper
  • Silver
  • Gold
  • Platinum
• Reactivity Series


  A league table for metals, with the more reactive metals near the top and the least reactive near the bottom
• A more reactive metal


  Will displace a less reactive metal in chemical reactions
• Reactions of metals with water

  1. Produce a metal hydroxide and hydrogen

  2. The more reactive the metal, the faster the reaction
• Metals, when reacted with water, produce a metal hydroxide and hydrogen
• The more reactive a metal is, the faster the reaction with water
• Reactivity of acids


  Metal is the
• Formula of reaction between acid and Metal

  Acid + metal -> salt + hydrogen
• Reaction between acid and alkali

  Acid + alkali -> salt + water
• When an acid reacts with an alkali, neutralisation reaction takes place, salt and water produced
• General formula: acid + alkali -> salt + water
• What are the key points to remember about electrolysis?

  • Electrolysis requires an electrolyte and electrodes.
  • Negatively charged ions move to the anode; positively charged ions move to the cathode.
  • Products depend on the reactivity of the ions and the presence of other substances.
• Why is it unsafe to react lithium, sodium, and potassium with dilute acids?

  They react so vigorously that it is not safe.
• What is the purpose of using inert electrodes in electrolysis experiments?

  Inert electrodes do not react with the electrolyte and allow for accurate observations.
• Which metals are considered fairly reactive?

  Calcium, magnesium, zinc, and iron.
• What is the relationship between oxidation and reduction?

  Oxidation and reduction always occur together.
• What is the role of the electrodes in electrolysis?

  They conduct electricity and facilitate the movement of ions.
• What is the general reaction for extracting iron from iron oxide using carbon?

  Iron oxide + carbon → iron + carbon dioxide.
• What are the ionic equations for the reaction between magnesium and oxygen?

  2Mg → 2Mg²⁺ + 4e⁻ and O₂ + 4e⁻ → 2O²⁻
• What is produced at the cathode during the electrolysis of aqueous sodium chloride?

  Hydrogen gas is produced.