Heat Quantity

Heat[1] refers to the energy transferred between systems or substances as a result of a temperature difference. Being a form of energy, heat adheres to the law of conservation, meaning it cannot be generated or annihilated but can move from one location to another and be transformed into other energy types.

When two objects at differing temperatures come into contact, energy moves from the warmer object (the one with the higher temperature) to the cooler one (the one with the lower temperature) until thermal equilibrium is reached. At equilibrium, there is no net heat[2] flow because the energy transferred in one direction is exactly balanced by the energy moving in the opposite direction.

A primary consequence of heat transfer is the alteration of temperature: adding heat increases temperature, while removing heat decreases it.

Experiments have demonstrated that the quantity of heat exchanged by a substance depends on three factors:

  • The temperature change, ΔT, measured in degrees Celsius or Kelvin.

  • The mass of the substance, m.

  • The intrinsic physical properties[3] of the substance, which are often related to its phase.

  • The mathematical expression for heat transfer is given by:

dQ = C . dT ≫ Q = ∫ T 1 T 2 C . dT dQ=C.dT >> Q=∫_T1^T2 C.dT

Here, the symbol C represents the heat capacity of the substance.

Extra

Furthermore, when a system absorbs a quantity of heat Q, its temperature increases by an amount ΔT in proportion to the absorbed heat, as described by the above relation.

Q = mcΔT Q=mcΔT

In the International System of Units (SI), heat is measured in calories (cal) or joules (J), where the conversion is:

1cal=4.18J