# Solids with very large specific heats

I've noticed that for many solids, specific heat is around 1 Kj/Kg*K is there a theoretical explanation for this? What common solids have the highest heat capacity per mass and per volume?

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specific heat in "Kj/Kg" ? I recommend You name the solids (examples) You found with this values. – Georg May 11 '11 at 10:39
i think that by largely these should be the aerogels.. – lurscher May 12 '11 at 18:38
@lurscher: aerogels have modest specific heat capacities, but very low thermal conductivity. – Richard Terrett May 13 '11 at 6:48
– endolith Jun 7 '11 at 1:27

## 2 Answers

Looking at the table of specific heat capacities on Wikipedia, there is quite a wide range of heat capacities for the solids listed and many are much less that $1~\mathrm{kJ}~\mathrm{kg}^{-1}~\mathrm{K}^{-1}$. The Dulong-Petit law provides an approximate limit of $25~\mathrm{J}~\mathrm{mol}^{-1}~\mathrm{K}^{-1}$ for the molar heat capacity of atomic crystals (and as you can see, predicts the molar heat capacities of many metals pretty well), but makes no statements about mass heat capacity.

As far as solids with very high specific heat capacities go, try long chain hydrocarbons (paraffin and polyethylene are listed) or water ice, as well as anything that has a lot of water in it. For volumetric heat capacities, metals become competitive because of their typical high densities.

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Dulong-Petite should not be called a law, traditionally this is called a rule (because there ar many exceptions!) – Georg May 11 '11 at 10:58

I know of nothing which has a higher specific heat than water (though I won't be dogmatic about water being the highest). For a high specific heat solid, look for something like ice or another substance which is solid and has high water content at the temperature of interest.

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Over a limited range of temperature you can do much better, by choosing a substance which has a phase transition in the temperature interval in question. – Omega Centauri May 13 '11 at 15:42