Unit 2 chem

• Rusting reaction


  GP = (Final volume - Start volume) / Total starting volume x 100
• Carbon dioxide


  Calcium carbonate + hydrochloric acid -> carbon dioxide (gas formed)
• Copper carbonate


  Thermal decomposition -> copper (green)
• Increase in carbon dioxide in atmosphere

  Increases the amount of energy retained by the Earth's atmosphere, leading to higher temperatures (climate change)
• Composition of the atmosphere


  • Nitrogen - 78%
  • Oxygen - 21%
  • Argon - 0.96%
  • Carbon dioxide - 0.04%
• Reaction of calcium carbonate with hydrochloric acid

  CaCO3(s) + 2HCl(aq) -> CO2(g) + CaCl2(aq) + H2O(l)
• Alkali metals


  Effervescent, react quickly, disappear quickly
• Halogens


  Most reactive group, diatomic, gain 1 electron to achieve stable electron configuration
• Displacement reaction


  A more reactive element displaces a less reactive element from a compound
• Reactivity series


  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Aluminium
  • Zinc
  • Iron
  • Lead
  • Copper
  • Silver
• All group 1 and 7 elements are diatomic
• Acid


  Turns red litmus paper, stays red with methyl orange, colourless with phenolphthalein
• Alkali


  Turns blue litmus paper, stays blue with methyl orange, pink with phenolphthalein
• pH scale


  0-3 strongly acidic, 4-6 weakly acidic, 7 neutral, 8-10 weakly alkaline, 11-14 strongly alkaline
• Neutralisation reaction


  Acid + Base -> Salt + Water
• Acid and base formulas


  • Hydrochloric acid - HCl
  • Sulfuric acid - H2SO4
  • Nitric acid - HNO3
  • Sodium hydroxide - NaOH
  • Calcium carbonate - CaCO3
• Salt


  Formed when the hydrogen of an acid is replaced by a metal
• Reactions of metals with acids


  1. Metals above hydrogen - metal + acid -> salt + hydrogen

  2. Metals below hydrogen - no reaction

  3. Metal oxide + acid -> salt + water

  4. Carbonate + acid -> salt + carbon dioxide + water
• Insoluble calcium carbonate layer forms, preventing further reaction with acid
• Solubility of salts


  • Soluble - nitrates, chlorides, sulfates
  • Insoluble - carbonates, hydroxides
  • Almost insoluble - exceptions to solubility rules