Temperature and Heat Transfer Basics

Temperature and Thermometry

• Temperature: a measure of the average kinetic energy of particles in a substance
• Thermometry: the measurement of temperature
• Common temperature scales:
  • Celsius (°C): water freezes at 0°C and boils at 100°C
  • Fahrenheit (°F): water freezes at 32°F and boils at 212°F
  • Kelvin (K): absolute temperature scale, water freezes at 273 K and boils at 373 K

Heat Transfer

• Heat: energy transferred from one body to another due to a temperature difference
• Three modes of heat transfer:
  1. Conduction: heat transfer through direct contact between particles
  2. Convection: heat transfer through the movement of fluids
  3. Radiation: heat transfer through electromagnetic waves (e.g. light, radio waves)

Heat Capacity and Specific Heat

• Heat capacity: the amount of heat energy required to change the temperature of a substance by 1°C
• Specific heat: the heat capacity of a substance per unit mass
• Units: J/kg°C or J/g°C

Latent Heat

• Latent heat: the heat energy required to change the state of a substance (e.g. solid to liquid, liquid to gas)
• Latent heat of fusion: the heat energy required to change 1 kg of a substance from solid to liquid
• Latent heat of vaporization: the heat energy required to change 1 kg of a substance from liquid to gas

Laws of Thermodynamics

• Zeroth Law: if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other
• First Law: energy cannot be created or destroyed, only converted from one form to another
• Second Law: the total entropy of a closed system always increases over time
• Third Law: as the temperature of a system approaches absolute zero, its entropy approaches a minimum value

Temperature and Thermometry

• Temperature is a measure of the average kinetic energy of particles in a substance.
• Thermometry is the measurement of temperature.
• Celsius (°C) scale: water freezes at 0°C and boils at 100°C.
• Fahrenheit (°F) scale: water freezes at 32°F and boils at 212°F.
• Kelvin (K) scale: absolute temperature scale, water freezes at 273 K and boils at 373 K.

Heat Transfer

• Heat is energy transferred from one body to another due to a temperature difference.
• Conduction: heat transfer through direct contact between particles.
• Convection: heat transfer through the movement of fluids.
• Radiation: heat transfer through electromagnetic waves (e.g. light, radio waves).

Heat Capacity and Specific Heat

• Heat capacity is the amount of heat energy required to change the temperature of a substance by 1°C.
• Specific heat is the heat capacity of a substance per unit mass.
• Units of heat capacity and specific heat are J/kg°C or J/g°C.

Latent Heat

• Latent heat is the heat energy required to change the state of a substance (e.g. solid to liquid, liquid to gas).
• Latent heat of fusion: the heat energy required to change 1 kg of a substance from solid to liquid.
• Latent heat of vaporization: the heat energy required to change 1 kg of a substance from liquid to gas.

Laws of Thermodynamics

• Zeroth Law: if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• First Law: energy cannot be created or destroyed, only converted from one form to another.
• Second Law: the total entropy of a closed system always increases over time.
• Third Law: as the temperature of a system approaches absolute zero, its entropy approaches a minimum value.