States of Matter T2

• Solid

  • Strong forces of attraction between particles
  • Particles held close together in a fixed position to form a regular lattice structure
  • Particles can vibrate in their position
  • when heated, particles gain more energy which weakens the forces between them. when reaches melting point, has enough energy to break free of the bonds. solid melts into liquid.
• Melting of a solid

  1. Particles gain more energy and start to vibrate even more

  2. Forces between particles weaken

  3. Particles have enough energy to break free of their bonds

  4. Solid melts into a liquid
• Liquid

  • Weak forces of attraction between particles
  • Particles free to move around and arranged randomly
  • Particles tend to stick together and are fairly compact
  • Liquids have a definite volume even though overall shape can change
  • when heated, particles gain more energy-> particles start to move faster. This weakens the forces holding the particles together. when reaches the boiling point, particles can have enough energy to break the bonds. liquid evaporates to a gas
• Boiling/Evaporation of a liquid

  1. Particles gain more energy and move around faster

  2. Forces holding particles together weaken

  3. Particles have enough energy to break the bonds

  4. Liquid boils or evaporates into a gas
• Gas

  • Very weak to no forces of attraction between particles
  • Particles free to move around by themselves
  • Gases don't keep a definite shape or volume and will fill a container
  • Particles move in straight lines but appear to have random motion due to deflections
  • when heated, gases may expand or the pressure is increase
• Expansion of a gas

  1. Particles gain more energy and travel faster

  2. Gas expands if container is expandable

  3. Pressure increases if container is fixed
• Condensation of a gas

  1. Particles lose enough energy that forces of attraction can form bonds

  2. Gas condenses into a liquid
• Freezing of a liquid

  1. Particles lose enough energy that more bonds form fixing them in place

  2. Liquid freezes into a solid
• Particle model used is a simplification - particles aren't actually solid, inelastic spheres but rather atoms, ions or molecules
• Particle model doesn't include details of the forces between particles
• Despite limitations, particle model is a useful simplification to understand the states of matter
• • at temperatures below the melting point, the substance will be solid
  • at temperatures above the melting point but below the boiling point, the substance will be liquid
  • at temperatures above the boiling point, the substance will be a gas
• In solids, strong attractive forces hold the particles in place, so that they can only vibrate in position. As the substance is heated, the particles gain energy and vibrate faster and faster. Eventually, the particles have so much energy that they can overcome the forces holding them together, and the substance melts into a liquid.
• When a gas is heated, the particles gain kinetic energy and move faster. If the gas is trapped within a container that cannot expand, it means that the volume of the gas is fixed, and so the pressure inside the container increases. 
• When a gas is heated..

  • If it's in a fixed container, the pressure will increase
  • If it's in an expandable container, the volume will increase
• In a closed system, changes in state won't change the mass at all. Why is this the case?

  The number of particles remain the same
• A mixture:

  Consists of 2 or more elements or compounds not chemically combined together

  Chemical properties of each substance in the mixture are unchanged
• A pure substance-> a single element or compound, not mixed with any other substance
• Pure substances melt and boil at specific/exact temperatures, mixtures do not:

  ● This means melting and boiling points data can be used to distinguish pure substances from mixtures (which melt over a range of temperatures due to them consisting of 2 or more elements or compounds)
• Simple distillation


  Used for separating out a liquid from a solution
• Equipment for simple distillation

  • Flask containing the solution/liquid mixture
  • Bung to seal the flask
  • Thermometer to measure temperature
  • Condenser with water jacket and cold water flow
  • Beaker to capture the pure liquid
  • Heating device like a Bunsen burner
• Simple distillation process

  1. Heat the mixture so the liquid evaporates

  2. Vapor passes through the condenser and condenses into liquid

  3. Collected in the beaker
• Simple distillation can be used to separate pure water from seawater
• Fractional distillation


  Main technique used for separating mixtures of liquids
• Equipment for fractional distillation

  • Flask containing the liquid mixture
  • Fractionating column with glass rods for high surface area
  • Condenser with water jacket and cold water flow
  • Beakers to collect the separated liquids
  • Heating device
• Fractional distillation process

  1. Heat the mixture to evaporate the lowest boiling point liquid

  2. Vapor rises up the fractionating column

  3. Cooler temperatures at the top cause higher boiling point liquids to condense and fall back into the flask

  4. Pure lowest boiling point liquid collects in the beaker

  5. Repeat the process to separate higher boiling point liquids
• Liquids that can be separated by fractional distillation

  • Methanol
  • Ethanol
  • Propanol
• Fractional distillation can separate a mixture of several liquids that each have different boiling points
• Separating soluble and insoluble solids from liquids

  1. Filtration

  2. Evaporation

  3. Crystallization
• Mixture


  Liquid and insoluble solid
• Solution


  Liquid and soluble solid, where the solid is the solute and the liquid is the solvent
• Filtration


  Use filter paper with tiny holes to separate insoluble solids from liquids
• Filtration cannot separate soluble solids from liquids
• Evaporation


  Place solution in evaporating dish/crucible, heat to evaporate solvent and leave behind solid crystals
• Evaporation

  • Relatively quick and easy, but some solids may undergo thermal decomposition
• Crystallization

  1. Place solution in evaporating dish, gently heat to evaporate some solvent, then allow to cool to form crystals

  2. Filter out crystals

  3. Dry the crystals
• Crystallization


  • Slower process, but avoids thermal decomposition of solids
• Solids are less soluble at colder temperatures
• if there is a solid in a liquid and it doesn't dissolve, then that is a mixture.
• Chromatography-> Used to separate mixtures and give information to help identify substances