I have read in many places that specific heat capacity is an property of the material but I haven't really understood what it depends upon, as in what factors affect that specific heat, I have thought of different things but none of them are consistent, especially when we consider degrees of freedom in each state, this argument fails to convince me as specific heats of liquids are more than solids and that gasses is much less than that of solids.

I would certainly appreciate it if some one could explain where this specific heat comes from and what are these "intrinsic factors" that affect specific heat capacity of solids liquids and gasses.


1 Answer 1


This is a complicated business which I will simplify a bit.

Heating an object causes its constituent atoms to randomly vibrate more vigorously. In so doing, the atoms are continuously exchanging kinetic energy back and forth between each other and so the bonds that connect those atoms are continually being exercised as well. So at any given instant in time, the total vibrational energy in the system is shared between the kinetic energy of the vibrating atoms and the potential energy of the distorted bonds between them.

This means that the system's capacity for absorbing heat energy per unit mass will depend on the atomic mass and on the exact nature of the bonds that hold the mass together. Those bonds are chemical in nature and can be ionic, covalent or metallic in a solid, and in a liquid they will be completely different- with the possibility of things like van der waals forces coming into the picture. Then in a gas, all of those considerations disappear and instead the gas atoms bounce off each other like billiard balls because those chemical bonds, whatever they might be, are absent or nearly so.

Note also that in a solid held together by metallic bonds, the outermost electrons are delocalized and hence capable of vibrating about through the atomic lattice as if they themselves were a sort of gas. This means that in a metal, the conduction electrons will make a significant contribution to the heat capacity, which you will not see in a solid that is held together by covalent bonds, where the bonding electrons are immobilized.

  • $\begingroup$ Thank you for your explanation @niels nielson could you please refer some articles which i could probably read to get to try to get to the heart of this matter $\endgroup$ May 25 at 16:54
  • $\begingroup$ i remember reading something on the last part of your answer, specifically regarding how electrons do not affect specific heat, The electrons in the metal which contribute to conduction are very close to the Fermi level. But to contribute to bulk specific heat, all the valence electrons would have to receive energy from the nominal thermal energy kT. But The Fermi energy is much greater than kT and the overwhelming majority of the electrons cannot receive such energy since there are no available energy levels within kT of their energy. $\endgroup$ May 25 at 16:58
  • $\begingroup$ The general problem of the specific heats of solids is dealt with in upper-level (college) materials science textbooks. $\endgroup$ May 25 at 17:11

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