States of matter

Cards (27)

  • Solids, Liquids and Gases
    Three states of matter that most substances exist in at room temperature
  • Solids
    • Have a fixed volume and fixed shape
    • Cannot flow because particles cannot move from place to place
    • Cannot be compressed because particles are close together and have no space to move into
  • Liquids
    • Have a fixed volume but no fixed shape
    • Can flow and take the shape of their container because particles can move around each other
    • Cannot be easily compressed because particles are close together and have no space to move into
  • Gases
    • Have no fixed shape or volume
    • Can flow and completely fill their container because particles can move quickly in all directions
    • Can be compressed because particles are far apart and have space to move into
  • Particle model
    Explains the difference between solids, liquids and gases
  • All substances are made up of particles
  • The particles are attracted to each other
  • Some particles are attracted strongly to each other and others weakly
  • The particles move around and have kinetic energy
  • The kinetic energy of the particles increases with temperature
  • Properties of solids, liquids and gases
    • Solids: Fixed volume and shape, cannot flow, cannot be compressed
    • Liquids: Fixed volume, no fixed shape, can flow, cannot be easily compressed
    • Gases: No fixed shape or volume, can flow, can be compressed
  • Changes of state
    Reversible changes due to changes in pressure or temperature, unlike chemical reactions no new substance is formed
  • Melting
    1. Solid changes into liquid
    2. Occurs at melting point
    3. Heat is absorbed during melting
    4. Impurities lower melting point and increase boiling point
  • Pure substances melt and freeze at the same temperature, impure substances melt and boil through a range of temperatures
  • During melting, heat energy is absorbed by the particles and converted to kinetic energy, causing the particles to vibrate faster and overcome attractive forces
  • Temperature remains constant during melting as the absorbed heat energy is used to weaken attractive forces between particles, not increase kinetic energy
  • Boiling
    1. Liquid changes into gas
    2. Occurs at boiling point
    3. Heat is absorbed during boiling
    4. Higher pressure results in higher boiling point
    5. Impurities affect boiling point
  • During boiling, heat energy is absorbed by the particles, increasing their kinetic energy until they have enough energy to overcome attractive forces and escape the liquid to form a gas
  • Temperature remains constant during boiling as the absorbed heat energy is used to weaken attractive forces between particles, not increase kinetic energy
  • Evaporation
    Liquid changes into gas, occurs at surface of liquid, no fixed temperature, takes place below boiling point
  • Condensation
    Gas changes to liquid when cooled to boiling point, heat is released to surroundings
  • Freezing
    Liquid changes into solid, occurs at freezing point, impurities lower freezing point
  • Sublimation
    Solid changes directly into gas, heat is absorbed, examples include dry ice, iodine, ammonium chloride
  • The state of a substance at a given temperature can be predicted if its melting and boiling points are known
  • Oxygen
    • Melting point -218°C, boiling point -183°C, so at -200°C oxygen will be in the liquid state
  • Heating curve
    Graphical representation of changes of state during heating, shows melting and boiling
  • Cooling curve

    Graphical representation of changes of state during cooling, shows condensation and freezing