Thermodynamics

• Specific heat capacity - energy required per mass of substance to raise the temperature by 1K
• Latent heat - energy transferred in a process without change in the body's temperature
• Specific latent heat - the amount of energy required to change the state of 1kg of a material without changing its temperature
• Specific latent heat of fusion - energy required per unit mass of a substance to change from solid to liquid phase without any change in temperature
• Specific latent heat of vapourization - energy required per unit mass of a substance to change from liquid to gas phase without any change in temperature
• The specific latent heat of vapourization of fusion is always greater than that of fusion

  • During vapourization, greater increase in volume than in fusion. Thus more work done against at atmosphere
  • During vapourization, particles need to be separated more further apart than in fusion, so more work is done against forces of attraction when vapourizing
• Internal energy - sum of all the randomly distributed kinetic and potential energies of molecules in a system
• Internal energy is determined by

  • temperature
  • state of matter
  • random motion of molecules
• Internal energy can be increased by

  • increasing temperature
  • doing work on it
• Internal energy can be decreased by

  • losing heat to its surroundings
• First law of thermodynamics - the increase in internal energy of a system is equal to the sum of the heat supplied to the system and the work done on the system
• Insotermal change - temperature remains constant, so the change in internal energy is zero