# Which is more stable: Ortho or Para Hydrogen? [duplicate]

It is known that Para-Hydrogen has opposite spin and Ortho-Hydrogen has same spin. Therefore, the energy of Para-Hydrogen is lower than that of Ortho-Hydrogen. Therefore, the stability order should be: Para-Hydrogen > Ortho-Hydrogen.

Is this true or is the stability order the opposite of what I predicted?. What is the reason for this stability order?

At room temperature, about $$75$$% of $$\ce{H2}$$ is $$\ce{o-H2}$$ and $$25$$% is $$\ce{p-H2}$$. As the temperature drops, the relative amounts of $$\ce{p-H2}$$ increases. The two forms are in a temperature-dependent equilibrium $$\ce{o-H2<=> p-H2}$$, $$\Delta H = \pu{-1.66 kJ/mol}$$.
Ref. M. Eagleson, Concise Encyclopedia Chemistry, Walter de Gruyter Berlin, New York $$1994$$, 1202 p. ISBN 0-89925-4547-8.