Units of Heat Energy

Units of Heat Energy

Heat changes are accompanied by changes in temperature.

•  If temperature increases or rises, heat is absorbed or gained.
• If temperature decreases or drops, heat is released or lost.

Heat is expressed in units of Joules (J), which is the SI unit of energy. The symbol for heat in our equations will be “q.”

 1000 Joules (J) = 1 kilojoule (kJ)

• Reactions which LOSE heat are called exothermic reactions. They may have negative (-) heat values.
• Reactions which GAIN heat are called endothermic reactions. They may have positive (+) heat values.

The non-SI but common unit for energy is the calorie or kilocalorie (kcal). We can convert between the two.

 1 kcal = 4.184 kJ