Substances

• States of matter

  Solid, liquid and gas
• freezing

  the change of state from liquid to solid
• Boiling point


  The temperature at which a substance boils
• Diffusion

  the net movement of particles from a region of higher concentration to a region of lower concentration due to their random movement
• Why is diffusion is typically a slow process


  Even though particles move at very high speeds, they collide with particles of air or water, slowing them down.
• Why do different substances diffuse at different speeds

  The mass of the particles may be different. the temperature of particles as well as the substance it is diffusing in also have an effect on the speed of diffusion
• Observations when liquid bromine is added to a gas jar

  the deep brown colour spreads out over the whole container, making it a moderate brown, through diffusion.
• Methods to separate mixtures of substances

  Filtration, evaporation (sometimes known as crystallisation) and distillation
• Rf value


  Of a substance on a chromatogram
• melting

  The change of state from solid to liquid
• evaporation

  The change of state from liquid to gas
• boiling

  The change of state from liquid to gas
• sublimation

  The change of state directly from solid to gas
• desublimation

  The change of state directly from gas to solid
• dissolving

  the process of a solute being mixed in with a solvent via collision. this breaks up the solute
• Rf value = distance travelled by the solute/distance travelled by the solvent
• filtration

  the process of separating a liquid from a solid by passing it through a filter. The solid is unable to pass through the filter, but the liquid is, as the particles in the liquid are smaller.
• distillation

  separating a liquid from a solution by heating the solution, so that the solvent evaporates and condenses in the condenser, leaving the solute behind in the distillation flask
• chromatography

  a technique used to separate mixtures of soluble substances, such as ink, based on their solubility.
• label the distillation apparatus

  A) distillation flask

  B) thermometer

  C) condenser

  D) collection flask

  
• difference between evaporation and boiling

  • boiling occurs only at a substance's boiling point whilst evaporation can occur at any temperature
  • boiling happens throughout the liquid whilst evaporation happens only on the surface
• arrangement of particles in a solid:

  • regular arrangement
  • vibrate on the spot
  • low energy
• arrangement of particles in a liquid:

  • regular arrangement
  • particles are close together and slide over each other
  • medium energy
• arrangement of particles in a gas:

  • irregular arrangement
  • fast and freely moving
  • high energy