The degree to which addition or removal of heat from a system results in a
temperature change depends on the
heat capacity of the system.
The
heat capacity (Cp) of a system is equal to the amount of energy in the form of
heat that must be added to
raise the temperature of the system
by 1 °C (or 1 K).
The unit of heat capacity is J °C
–1 (or J K
–1).
Therefore heat (
q), heat capacity (
C) and the change in temperature (Δ
T) are related mathematically as shown below.
q = CpΔT
ΔT = Tfinal -Tinitial
It is important to appreciate that the temperature can either go up or go down.
Therefore the
change in temperature (Δ
T) can be either
positive or negative.
Thus
q can be either positive or negative.
If q is positive, heat has been transferred to the object in question.
If q is negative, heat has been transferred from the object in question.
It is important to note that the heat capacity and change in temperature are multiplied together to give heat.
This means that for the same quantity of heat the change in temperature will be smaller if the heat capacity is larger and vice versa.