States of matter and mixture

• Particle

  A molecule, ion or atom
• Solid

  • Strong forces of attraction between particles
  • Particles held in fixed positions in a regular lattice arrangement
  • Particles don't move from their positions
  • Solids keep a definite shape and volume
  • Particles have little energy
  • Particles can only vibrate about their fixed positions
  • Hotter solids vibrate more, causing expansion
• Liquid

  • Some force of attraction between particles
  • Particles free to move past each other
  • Particles tend to stick together
  • Liquids don't keep a definite shape
  • Liquids will flow to fill the bottom of a container
  • Liquids keep the same volume
• Adding heat to a solid

  Increases the vibration of particles
• The forces between particles determine whether a substance is a solid, liquid or gas
• Gases

  • There's next to no force of attraction between the particles
  • Particles travel in straight lines and only interact when they collide
  • Gases don't keep a definite shape or volume and will always fill any container
  • When particles bounce off the walls of a container they exert a pressure on the walls
  • Particles have more energy in the gas state than in the solid or liquid state
  • Particles move constantly with random motion
  • The hotter the gas gets, the faster the particles move
  • Gases either expand when heated, or their pressure increases
• • When a solid is heated its particles gain more energy
  • making particles vibrate more
  • weakening forces that hold the solid together, making it expand
  • Melting - at a certain temp particles have enough energy

  to break free from their position
• gas to solid

  Deposition
• Solid to gas

  Sublimation
• • liquid to gas
  • When a liquid is heated the particles get more energy
  • making particles move faster , weakening and breaking bonds holding the liquid together
  • at a certain temp Particles have enough energy to break their bonds called evaporating
• Chemical reactions result in chemical changes 


  bonds between atoms break and atoms change place
• Pure

  Made up of a single element or compound
• Pure substances have sharp melting and boiling points
• Mixtures melt over a range of temperatures
• Simple distillation is used to separate a liquid from a solution
• Solute

  substance that dissolves in a solvent
• Solution

  Mixture of when a solute dissolves in a solute
• Fractional distillation 


  Used to separate a mixture of liquids with close boiling points
• In simple distillation there’s anti bumping granules 


  That decrease the risk of large bubbles boiling over
• The top of the column is the coolest 


  The bottom of the Column is the hottest

  
• Filteration


  Separates insoluble solid from a liquid
• Crystallisation


  Separates a soluble solid from a solution
• Chromatography 


  Separate a mixture of coloured compounds to their individual components
• Mobile phase 


  Where molecules can move (liquid or gas)
• Stationary phase 


  Where molecules can’t move
• Calculating R₁

  Using the formula: R₁ = distance travelled by solute / distance travelled by solvent
• Chromatogram 


  Paper at end of chromatography
• Solvent front


  Highest point mobile phase reaches
• Rf value will always be below 1
• Chromatography

  separation of mixtures of soluble substances by running a solvent (mobile phase) through the mixture on the paper (the stationary phase), which causes the substances to move at different rates over the paper
• Core practical - investigate composition of inks using simple distillation and paper chromatography 


  Instructions

  
• Potable water 


  Water that’s safe to drink
• • Surface water : from lakes and reservoirs
  • ground water : from aquifers
  • waste water : contaminated by human processes
• sea water is made potable using distillation 


  • Problems : lots of energy required - expensive
  • for energy, fossil fuels are combusted
  • benefits - hot and dry counties use it
• Water used in chemical tests must be deionised water 


  which is water that has ions removed that are present in tap water
• Tap water contains ions that can alter with chemical analysis results
• Waste and ground water are purified through sedimentation , filtration , chlorination
• Sedimentation

  water flows very slowly allowing large and insoluble substances to settle to the bottom
• Filtration

  Wire mesh screens out leftover insoluble substances
• Chlorination

  Chlorines bubbled through the water to kill microorganisms like bacteria