Heat – The kinetic energy due to random motion of the molecules of a substance is known as its heat energy. Each body possesses heat energy in form of its internal kinetic energy.
Calorimetry – The measurement of the quantity of heat is called calorimetry.
Temperature – The average internal kinetic energy of molecules of a substance is a measure of the temperature of that substance.
- For two bodies in contact, heat flows from a body at a higher temperature to a body at a lower temperature.
- It is the temperature which determines the direction of flow of heat.
Principle of calorimetry
- When a hot body is mixed or is kept in contact with a cold body, heat energy passes from the hot body to the cold body, till both the bodies attain the same temperature.
- If no heat energy is exchanged with the surroundings, i.e., if the system is fully insulated, then
- Heat energy lost by the hot body= Heat energy gained by the cold body.
- For two bodies A and B in contact and at temperatures TAand TB respectively, such that TA> TB, we have from the principle of calorimetry the equation:
- mAcA(TA – T) = mBcB (T – TB).