Specific Heat

Specific Heat

Temperature: If temperature is measures in Kelvin, then its value is directly proportional to the average kinetic energy of the molecules of a substance.

Heat: Actual energy measured in joules or other energy units

•   Heat is a flow of energy due to a temperature difference

Thermal Energy: Flow of energy called heat, transferred from a hot object to a colder object.

• Thermal energy refers to the amount of energy in a sample
  • It is dependent on both mass and temperature of the sample
  • Because heat is a process of energy transfer, it is incorrect to refer to the "heat energy of a sample" the correct term is "thermal energy of a sample"

Heat Flow

• Heat flow is measured in two common units: the calorie and the joule
  • The energy in food is expressed in kilocalories (kcal)
  • 1 kcal = 1000 calories

Units of Energy

• The calorie or joule is a unit of energy used to measure heat transfer and to express thermal energy
• It takes one calorie of heat to raise the temperature of one gram of water by one degree Celsius
  • It takes 4.184 joules to raise the temperature of one gram of water by one degree Celsius. This is known as the specific heat of water

Specific Heat Capacity

• There are two factors that the heat capacity of an object depend on:
  • Mass (g)
  • Chemical composition- what the material is made of

Specific Heat Capacity Equation

• We use the following equation: q = m x C x ΔT
  • q = heat (joules or calories)
  • m = mass (grams)
  • ΔT = change in temperature (°C)