(6.2) Thermal Physics

• What is the internal energy of a body equal to?

  Sum of all kinetic and potential energies
• How is the internal energy of a system increased?

  By doing work or increasing temperature
• What happens to internal energy when a substance changes state?

  Internal energy changes due to potential energy change
• What occurs to the temperature of water as it boils?

  Temperature remains constant after 100°C
• What is the formula to measure energy required to change temperature?

  Q = mcΔθ
• What does specific heat capacity measure?

  Energy required to raise 1 kg by 1°C
• What is the formula for energy required to change state?

  Q = ml
• What is specific latent heat?

  Energy required to change state without temperature change
• What are the two types of specific latent heat?

  • Specific latent heat of fusion (solid to liquid)
  • Specific latent heat of vaporisation (liquid to gas)
• How do you calculate time taken using power and energy?

  t = Q / P
• How much energy is required to heat 0.5 kg of water from 22°C to 100°C?

  163800 J
• How long does it take for the kettle to heat the water?

  136.5 seconds
• What is the final temperature of water after an ice cube melts?

  14.3 °C
• What is the specific heat capacity of water?

  4200 J/kg°C
• What is the specific latent heat of fusion of ice?

  334000 J/kg
• What do the gas laws describe?

  Relationship between pressure, volume, and temperature

  
• What is Boyle's Law?

  Pressure and volume are inversely proportional

  
• What is Charles' Law?

  Volume is directly proportional to absolute temperature
• What is the Pressure Law?

  Pressure is directly proportional to absolute temperature
• What is the absolute scale of temperature?

  The Kelvin scale
• How do you convert Celsius to Kelvin?

  K = C + 273
• What is absolute zero?

  -273°C or 0 K
• What does the ideal gas equation represent?

  Relationship between pressure, volume, and temperature

  
• What is the molar gas constant?

  8.31 J mol⁻¹ K⁻¹
• How do you calculate work done on a gas?

  W = pΔV
• What is Brownian motion?

  Random motion of larger particles in a fluid
• How does Brownian motion support atomic theory?

  • Evidence for existence of atoms and molecules
  • Observed through smoke particles under a microscope
• How can the gas laws be explained using a molecular model?

  • Boyle's Law: Pressure inversely proportional to volume
  • Charles's Law: Volume directly proportional to temperature
  • Pressure Law: Pressure directly proportional to temperature
• What is the formula for work done in terms of pressure and change in volume?

  $W =$$p \Delta V$
• How is work done represented on a pressure-volume graph?

  It is the area under the graph.

  
• What is Brownian motion?

  Random motion of larger particles in a fluid.
• What causes Brownian motion?

  Collisions with surrounding particles.
• What does Brownian motion provide evidence for?

  Existence of atoms and molecules.
• What are the gas laws explained by the simple molecular model?

  • Boyle’s law: Pressure inversely proportional to volume.
  • Charles’s law: Volume directly proportional to temperature.
  • Pressure Law: Pressure directly proportional to temperature.
• What happens to pressure when the volume of a gas increases at constant temperature?

  Pressure decreases.

  
• What occurs to gas molecules when temperature increases at constant pressure?

  They move further apart, increasing volume.
• What happens to pressure when the temperature of a gas increases at constant volume?

  Pressure increases.
• What is the nature of the gas laws?

  They are empirical in nature.
• What is the kinetic theory model based on?

  It arose from theoretical assumptions.
• What are the assumptions of the kinetic theory model?

  • No intermolecular forces act on molecules.
  • Duration of collisions is negligible.
  • Molecules experience perfectly elastic collisions.
  • Molecules follow Newton’s laws.
  • Molecules move in straight lines between collisions.