C2

• What are the three states of matter?

  Solids, liquids, and gases
• How are particles arranged in solids?

  Strong forces hold particles in a fixed arrangement
• How do particles move in solids?

  Particles vibrate about their fixed positions
• How are particles arranged in liquids?

  Weaker forces hold particles close but movable
• How do particles move in liquids?

  Particles move in random directions at low speeds
• How are particles arranged in gases?

  No forces of attraction between gas particles
• How do particles move in gases?

  Particles move freely and randomly at high speeds
• Which state of matter has the lowest relative energy?

  Solids
• Which state of matter has the highest relative energy?

  Gases
• What is the process of solid to liquid called?

  Melting
• What is the process of liquid to gas called?

  Boiling
• What is the process of gas to liquid called?

  Condensing
• What is the process of liquid to solid called?

  Freezing
• What is the process of solid to gas called?

  Sublimating
• What type of changes are changes of state?

  Physical changes
• What is a physical change?

  Change in arrangement or energy of particles
• Are physical changes reversible or irreversible?

  Reversible
• What happens when a substance melts from solid to liquid?

  Particles gain energy and vibrate more
• What happens when a substance boils from liquid to gas?

  Particles gain energy and move faster
• What happens when a substance condenses from gas to liquid?

  Particles lack energy to overcome attraction
• What happens when a substance freezes from liquid to solid?

  Particles lack energy to overcome attraction
• What are chemical changes?

  Irreversible changes forming new products
• What does "pure" mean in everyday life?

  Clean or natural
• What does "pure" mean in chemistry?

  Made of only one element or compound
• What is a mixture?

  Contains more than one compound
• How to separate mixtures by simple distillation?

  • Heat mixture in distillation flask
  • Lowest BP part evaporates
  • Vapour rises to condenser
  • Cools and collects in container
  • Higher BP parts remain in flask
• How to separate mixtures by fractional distillation?

  • Heat mixture
  • Lowest BP liquid evaporates first
  • Vapour reaches top of column
  • Cools, condenses, and collects
  • Raise temperature for next lowest BP
• What happens when other liquids with higher BPs start to evaporate in fractional distillation?

  They move up the column and condense
• How to separate mixtures by filtration?

  • Pour mixture through filter paper
  • Liquid passes through, solid remains
  • Place filter paper in funnel over flask
• How to separate solids by crystallisation?

  • Heat solution in evaporating dish
  • Crystals form as solution cools
  • Filter crystals and dry in warm place
• How to separate soluble coloured substances using chromatography?

  • Place sample on pencil line of chromatography paper
  • Immerse paper in solvent
  • Remove and dry after solvent travels 2/3 up
• Why should the line on chromatography paper be drawn in pencil?

  Pencil doesn't dissolve in solvent
• Why should ink spots be above solvent level in chromatography?

  To prevent dissolving in solvent
• What is meant by a solvent front?

  Furthest distance reached by the solvent
• How can chromatography determine if a substance is present in a mixture?

  Compare Rf value with pure substance
• Why should chromatography paper be removed before solvent reaches the top?

  To measure distance for Rf value calculation
• What are the two phases in chromatography?

  Mobile phase and stationary phase
• What is the mobile phase in chromatography?

  The solvent carrying substances
• What is the stationary phase in chromatography?

  The paper on a glass plate
• What is the formula for Rf value?

  $Rf =$$\frac{Distance\ travelled\ by\ substance}{Distance\ travelled\ by\ solvent}$