Zeroth Law of Thermodynamics:
There is a state function, called temperature which has
the symbol T, which has the following relationship to
heat, q :
- addition of heat to a system will increase the temperature
of the system.
- if two closed system (together isolated), with different
temperatures are brought into thermal contact, then the temperatures
of the two systems will change to approach the same temperature.
That is, the temperature of the system which is at a higher temperature
will decrease and the temperature of the system with the lower temperature
will increase. They will eventually have the same temperature.
For a schematic of this concept
The zeroth law leads to
the general idea of heat capacity. The symbols Cp
and C v are used for this (constant pressure
and constant volumn) but for solid there is usually little difference
between these two. Using the relationship at constant volume (and
therefore Cv ) between a change in temperature, Δ
T , of a substance and the amount of heat transferred,
q, to this substance is given by:
q = Cv ΔT
At constant pressure:
q = Cp ΔT
If one uses the concept
of a molar heat capacity, Cv
or Cp , where the bolding indicates a per mole quantitiy, then for
a simple compound one may write:
q = n Cv ΔT
or
q = n Cp ΔT