C5: chemical changes

• When analysing the reactivity of different metals, you can determine the reactivity by putting the metal in hydrochloric acid or water and counting the number of bubbles that come off
• Reactivity series of metals

  • Potassium
  • Sodium
  • Calcium
  • Magnesium
  • Aluminium
  • Zinc
  • Iron
  • Tin
  • Lead
  • Copper
  • Mercury
  • Silver
  • Gold
• Mnemonic to remember the reactivity series


  Please stop calling me a careless zebra instead try learning how copper saves gold
• Displacement reaction to determine reactivity

  1. Add copper sulfate to magnesium

  2. Magnesium displaces copper

  3. Magnesium sulfate and copper formed
• Observations in displacement reaction

  • Blue solution discolourises
  • Bronze solid forms
• Oxidation and reduction in displacement reactions

  • Copper 2+ goes to copper (reduction)
  • Magnesium goes to Mg 2+ (oxidation)
• Redox reaction

  One species is reduced and the other is oxidised
• Extracting metals from oxides using hydrogen or carbon


  1. Hydrogen reacts with copper oxide to form water and copper

  2. Carbon reacts with copper oxide to form carbon dioxide and copper
• Reaction of metals with acids

  Makes salt and hydrogen
• Types of salts formed

  • Chlorides
  • Nitrates
  • Phosphates
  • Sulfates
• Making salts from metal oxides and acids

  1. Add oxide to acid

  2. Filter out unreacted solid

  3. Evaporate water

  4. Crystallise product
• Reaction of metal carbonates with acids

  Makes salt, water and carbon dioxide
• Acid

  Contains H+ ions
• Alkali

  Contains OH- ions and is soluble in water
• Strong acid

  Fully dissociates in water (e.g. hydrochloric acid)
• Weak acid


  Partially dissociates in water (e.g. ethanoic acid)
• pH scale

  Measures hydrogen ion concentration, lower pH means higher [H+]
• Diluting a strong acid

  Decreases pH by 1 unit for every 10x dilution