substances and states of matter

• Solids


  • Can melt when heated
  • Particles are arranged closely packed together
• Liquids


  • Particles are mainly touching but easily slide past each other
  • Flow to take the same shape as the bottom of their container
• Gases


  • Particles move randomly and very far apart
  • Easy to compress
  • Spread out until they fill their container
• Evaporation


  Turning from a liquid to a gas
• Evaporation takes place at most temperatures but it helps for the liquid to be warmed up
• Solids


  • Particles don't move relative to others but do vibrate around a fixed position
  • Can't be poured because their particles are in a fixed position
• Boiling


  Occurs when the particles are moving fast enough to break all the forces of attraction
• For evaporation only some particles need to move fast enough
• When particles are heated


  They move faster because they have more energy
• Gas particles move faster as they become hotter and again kinetic energy
• Matter

  All physical stuff
• Energy of particles


  Solid < Liquid < Gas
• Melting point = solid to liquid
• Boiling point


  liquid to gas
• Condensation


  gas to liquid
• Boiling happens at exactly the boiling point
• Boiling happens everywhere in the liquid at once
• dissolving = the process of a substance (usually solid) breaking away from one another and starting to mix in with another substance (usually liquid)
• solvent = a substance (usually liquid) that can dissolve a solute
• solute = a substance (usually solid) that dissolves into a solvent
• solution = the mixture formed when a solute dissolves in a solvent
• soluble = a substance that can dissolve in a solvent
• insoluble = a substance that cannot dissolve in a solvent
• diffusion = movement of particles from a region of higher concentration to a region of lower concentration due to their random movement
• sublimation = solid to gas
• deposition = gas to solid
• freezing = liquid to solid
• diffusion is usually a slow process even when particles move at very fast speeds due to collisions with air particles or water
• when liquid bromine is added to a gas jar:

  • at first there is high concentration of bromine at the bottom of the jar but zero concentration at the top
  • then there is high concentration of bromine at the bottom of the jar and low concentration of bromine at the top
  • by the end of the experiment there is an even concentration throughout the jar
• process responsible for the reduction in volume of liquid bromine at the bottom of the jar = evaporation
• why does the region above the liquid bromine darken in colour?


  the evaporated gas is spreading above the liquid to fill more of the tube against the resistance of air particles which collide with it
• how does the concentration of bromine vapour throughout the jar change over time?

  1. bromine is all concentrated at the bottom of the jar
  2. bromine spreads from the area of high concentration to low concentration after a few minutes
  3. by the end of the experiment, the bromine has finished diffusing and there's even concentration throughout the jar
• particle = something made of atoms and matter
• Rf value = distance travelled by substance/distance travelled by solvent front
• substances diffuse at different speeds due to different particle mass

  • if a substance has heavier particles it will diffuse slower as they move slower
• evaporation lab apparatus:

  • stirring rod
  • bunsen burner
  • evaporating dish
• lab apparatus for filtration:

  • filter paper
  • funnel
  • conical flask
  • beaker
• 
  

  observations in ammonia hydrogen chloride experiment

  
  

  each liquid(hydrogen chloride/ammonia) is evaporating off the cotton wool. the white solid is further to the right of the glass tube (the side with the hydrogen chloride) because the ammonia solution has a smaller atomic mass and will therefore move faster and further than the ammonia in the same amount of time.
• ammonia hydrogen chloride experiment...

  it takes a few minutes for the white solid to form even though gas particles move at high speeds because the gas particles don't travel in a straight line and face multiple collisions which may interfere with the molecules in the air which overall slows down their movement speed
• filtration is the process in which solid particles in a liquid are removed by the use of a filter medium