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P6 Molecules and Matter (Gas Pressure (& Temperature (increasing…

- - - - density of water
        
        objects with densities lower than 1g/cm³ floats
- - - - particles vibrate
        
        fixed postion
        
        solid has fixed shape
        
        least energy
      - particles next to eachother
        
        strong intermolecular forces
    - - particles move at high speed
        
        in random directions
        
        most energy
      - particles far apart
        
        negligible forces of attraction
        
        low density
    - - particles move
        
        at random
        
        can flow
      - particles in contact
        
        weaker intermolecular forces
  - - - no new substances produced
        
        conservation of mass
      - can be reversed
    - - Melting point
        
        = Freezing point
        
        liquid >> solid
        
        solid >> liquid
        
        water freezes at 0°C
      - Boiling point
        
        temperature at liquid >> gas
        
        Boiling takes place throughout liquid at boiling point
        
        Evaporation takes place at surface of liquid below boiling point
        
        Evaporation causes cooling as high energy particles escape
        
        gas >> liquid (condenses)
        
        water boils at 100°C
    - - energy transferred to or from substance
        
        Latent Heat
        
        temperature does not change during state change
        
        'flat' sections on temperature-time graphs
    - - the energy needed to change the state 1kg of substance
        
        with no change in temperature
        
        of Fusion
        
        from solid to liquid
        
        of Vaporisation
        
        from liquid to vapour
      - E = m Lf
        
        Energy = Mass x Specific Latent heat of fusion
      - E = m Lv
        
        Energy = Mass x Specific Latent heat of vaporisation
- - - - individual motions relative to eachother
    - - individual positions relative to eachother
      - chemical stores in particle bonds
  - - - temperature increases
    - - change of state
- - - - with each other and the walls of the container
      - exerting a force of the surface of walls
      - produces a steady pressure on walls from total force
        
        Pressure is force per unit area
        
        p = F ÷ A
  - - - pressure increases
        
        particles move faster
        
        collides with more force
        
        more collisions each second
  - - - smoke particles pushed by random erratic motion of air molecules
  - - - no. of gas molecules is constant (mass)
        
        average speed of gas is constant (temperature)
      - reducing volume
        
        molecules have less space to move and don't travel far
        
        no. of collisions per second increases
        
        force per unit area (pressure) increases
      - Boyle's Law
        
        p V = constant
        
        Pressure x Volume = Constant
        
        pressure is inversely proportional to the volume of gas
    - - Slowly
        
        energy transferred to surroundings by heating
        
        internal energy store and temperature does not change
      - Quickly
        
        energy not transferred quickly enough to surroundings
        
        work done increases internal energy store and temperature (of gas)