C4 Chemical Changes

• What does a metal + oxygen make?


  Metal oxide
• Oxidation is the gain of oxygen
• Reduction is the loss of oxygen
• Oxidation is the loss of electrons
• Reduction is the gain of electrons
• Metal + hydrochloric acid = metal chloride and hydrogen
• Metal + sulfuric acid = metal sulfate and hydrogen
• Metal + nitric acid = metal nitrate and hydrogen
• Reactivity series

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Aluminium
  • Carbon
  • Zinc
  • Iron
  • Hydrogen
  • Copper
  • Silver
  • Gold
  • Platinum
• What is displacement?

  When more reactive metals take the place of less reactive metals in a reaction
• Extraction of metals

  • Reduction with carbon - metals that are less reactive than carbon can be removed from their ores
  • Electrolysis - metals more reactive than carbon are removed by electrolysis
• Metals that are unreactive don’t need displacing because they are found as a native metal
• What does the PH scale measure?


  How acidic or alkaline a substance is
• What do acids form when added to water?

  Form H+ ions
• What do alkalis form when added to water?

  OH- ions
• What are OH- ions?


  Hydroxide
• Acid + base = salt and water
• What is a neutralisation?


  Acid and a base form salt and water
• What are the 3 types of base?

  Oxide, hydroxide, carbonate
• What are the 3 main types of acid?

  Hydrochloric acid, sulfuric acid, nitric acid
• Symbol for hydrochloric acid?


  HCl
• Symbol for sulfuric acid?


  H2SO4
• Symbol for nitric acid?


  HNO3
• Titrations - increasing accuracy

  • Repeat titrations - rough titration (add bit by bit) then accurate titrations (drop by drop)
  • Calculate a mean from repeated results
• What indicator is used for titrations?


  Single indicators eg phenolphthalein, litmus, methyl orange
• Why shouldnt you use universal indicators in titrations?

  Too vague, doesn’t show sudden colour change
• Strong vs weak acids

  • Acids ionise in aqueous solutions - produce H+ ions
  • Strong acids - fully ionise in water, all particles dissociate to release H+ ions
  • Weak acids - don’t ionise fully in water, small number of particles dissociate to release H+ ions
• Ionisation of weak acids is a reversible reaction
• Weak acid

  • Ionisation is reversible
  • sets up an equilibrium between undissociated and dissociated acid
• What is the PH of an acid or alkali?


  How many H+ ions are in the solution
• For every decrease of 1 on PH scale, conc of H+ ions increases by a factor of 10
• Metal + oxygen = metal oxide
• Metal + hydrochloric acid = metal chloride + hydrogen
• Metal + sulfuric acid = metal sulfate + hydrogen
• Metal + nitric acid = Metal nitrate + hydrogen
• Oxidation = loss of electrons
• Reduction = gain of electrons
• OILRIG

  • Oxidation is loss
  • Reduction is gain
• Metal + acid = salt + hydrogrn
• Halogen displacement

  • More reactive halogen displaces less reactive halogens from salt solutions