# What is the substance with the highest specific heat?

I always learned that water has the highest specific heat, but I recently saw that hydrogen has a specific heat as high as $$\pu{14 cal g^-1 °C^-1}$$ and helium has a specific heat of $$\pu{5 cal g^-1 °C^-1},$$ which would be much higher than water? Is this true? and how can it be if there are so many “proofs” in nature, showing that water has the highest specific heat?

• – A.K.
Oct 30, 2018 at 1:13
• Yes, that's true, except that the figures are in Joules, not calories. Still, they are a good deal bigger than that for water. There is nothing strange or anomalous about it. Oct 30, 2018 at 6:01
• You would be better to compare heat capacity in joules/mole/K rather than mass, in that case hydrogen is approx 28 , water approx 75, but for example benzene 117 and anthracene 211. Oct 30, 2018 at 10:00
• I bet the interior of the sun has a very high specific heat. Jun 23, 2021 at 0:17

This may not be the absolute highest, but on a mass basis hydrogen gas has more than three times the specific heat as water under normal laboratory conditions. Diatomic gases under ambient conditions generally have a molar specific heat of about $$\pu{7 cal mol^-1 K^-1},$$ and one mole of hydrogen has only $$\pu{2 g}$$ mass. Thus $$\pu{3.5 cal g^-1 K^-1}$$ for hydrogen versus $$\pu{1 cal g^-1 K^-1}$$ for water.
Helium, contrary to the question, is $$\pu{5 cal mol^-1 K^-1},$$ not $$\pu{7 cal g^-1 K^-1}.$$