Chapter 14- Thermal physics

Chapter 14- Thermal physics

1. The triple point of a substance- "one specific temperature where the 3 phases of matter exist in thermal equilibrium"

   • Thermal equilibrium- "A state in which there is no net flow of thermal energy between the objects involved"
     • Objects in thermal equilibrium must be at the same temperature
       • Zeroth law- "If 2 objects are each in thermal equilibrium with a third, then all 3 are in thermal equilibrium with each other

2. Celsius scale

   • °C
   • Uses triple point of water and absolute zero
   • Increment change is the same size as the Celsius scale
   • K=θ°C+273

3. Absolute scale

   • Kelvin (K)
   • Uses 2 fixed points (Boiling water & freezing point of water
   • 100 increments (Between 0°C and 100°C)

4. The Kinetic model

   • There are 3 main phases
     • Solid
     • Liquid
     • Gas

5. Internal energy- "The sum of the randomly distributed kinetic and potential energies of atoms/molecules within the substance

   • Kinetic energy is determined by the temperature of the susbstance
   • Forces of attraction between particles determines potential energy (This is always negative)

6. Specific heat capacity

   • "The energy required per unit mass to change the temperature by 1K/1°C
   • Jkg^-1K^-1
   • c=E/(m*Δθ)
   • Water has exceptionally high specific heat capacity

7. Specific latent heat

   • "The energy required to change the phase per unit mass while at constant temperature"
     • L=E/m
     • A substance still requires energy to change phase even when at its melting or boiling point.
   • Specific latent heat of fusion (Lf)
     • Solid--> Liquid
   • Specific latent heat of vapourisation (Lv)
     • Liquid--> Gas
   • For this to occur the other way the substance must transfer the latent heat energy to its surroundings

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