changes of state

• conservation of mass


  mass is conserved during a change of state of a substance.
• change of state

  A) liquid

  B) sublimation

  C) condensing

  D) melting

  
• physical changes can be reversed [such as changing state] but chemical changes cannot be reversed.
• specific heat capacity is the amount on energy required to raise 1 kg of a substance by 1℃

  energy = mass x specific heat capacity x change in temperature
• specific heat capacity equation


  E = mcT

  energy = mass x specific heat capacity x CHANGE in temperature
• specific latent heat is the energy required to change the state of 1 kg of a substance.
• specific latent heat equation


  E = mL

  energy = mass x specific latent heat
• specific latent heat of fusion is the changing of state between solids and liquids, --> freezing and melting
• specific latent heat of vaporisation is the changing of state between liquid and gas, --> boiling and condensing.
• latent heat is used when there's no change in temperature during phase transitions (melting/freezing or evaporation/condensation).
• PAG - specific heat capacity

  
• PAG - specific heat capacity


  1. use a mass balance to weigh the mass of the substance
  2. make sure the joulmeter reads 0
  3. measure the initial temperature of the substance and turn the power on.
  4. when the temperature has increased by a fixed amount [e.g. 10 degrees] record the energy on the joulemeter and the temperature increase.
  5. calculate the specific heat capacity
  6. repeat and calculate a mean
  7. use an insulating container and watch for systematic errors due to energy dissipating to the surroundings.
• ways a substance can change state

  1. sublimation
  2. freezing
  3. melting
  4. evaporating
  5. condensing
• sublimation: when a substance transitions from a solid to a gas without transitioning to a liquid in between
• internal energy [of a substance]: energy stored by the particles, sum of kinetic energy and potential energies