3.2.4 Specific Latent Heat

• Latent heat

  The amount of heat energy required to change the state of a unit mass of a substance without changing its temperature
• Types of Latent Heat

  • Latent Heat of Fusion
  • Latent Heat of Vaporization
• Latent Heat of Fusion

  The energy required to change a substance from a solid to a liquid at its melting point (or vice versa)
• Latent Heat of Vaporization

  The energy required to change a substance from a liquid to a gas at its boiling point (or vice versa)
• Latent Heat Formula

  1. Q=mL

  2. Q=mL_f

  3. Q=mL_v
• Q

  Heat energy (in joules, J)
• m

  Mass of the substance (in kilograms, kg)
• L


  Latent heat (in joules per kilogram, J/kg)
• Melting Ice

  1. Ice absorbs heat

  2. Breaks hydrogen bonds

  3. Changes to water
• Boiling Water

  1. Water absorbs heat

  2. Converts from liquid to gas

  3. Overcomes intermolecular forces

  4. Escapes as steam
• Factors Affecting Latent Heat

  • Material
  • Temperature and Pressure
  • Impurities
• Material

  Different substances have different latent heats due to the nature of their intermolecular forces
• Temperature and Pressure


  Latent heat values can change with temperature and pressure
• Impurities

  Impurities can affect the latent heat of a substance, changing the energy required for phase changes
• Real-World Applications


  • Weather and Climate
  • Refrigeration and Air Conditioning
  • Cooking
• Role in Weather

  Latent heat plays a significant role in weather phenomena such as cloud formation and storm development
• Principle of Refrigeration and Air Conditioning


  These systems use the principles of latent heat to remove heat from a space
• Applications in Cooking

  Cooking processes rely on latent heat to change the state of food substances
• Latent Heat is crucial in understanding and managing phase changes in natural processes and technological applications
• Understanding latent heat helps explain various physical processes, from everyday boiling and melting to complex natural phenomena and engineering systems