Q.How do you convert para hydrogen into ortho hydrogen?

Heating pure para hydrogen to a high temperature (or exposing it to a catalyst/electric discharge) converts some of it into ortho hydrogen, until the equilibrium 3:1 ortho:para ratio (ordinary/normal hydrogen) is reached.

Hydrogen exists in two nuclear-spin isomeric forms, differing in whether the spins of the two nuclei (protons) in the H2 molecule are aligned in the same direction (ortho hydrogen, parallel spins) or in opposite directions (para hydrogen, antiparallel spins). Ortho hydrogen is slightly higher in energy than para hydrogen, and at very low temperatures (near absolute zero) essentially all hydrogen exists as para hydrogen, since it is the lower-energy, more stable form under those conditions.

As the temperature is raised, some of the para hydrogen molecules absorb enough energy to flip one nuclear spin and convert into ortho hydrogen. This conversion is normally very slow because it requires a change of nuclear spin, which is a spin-forbidden, and hence sluggish, process. To make the conversion happen at a useful rate, the sample is either:

1. Heated strongly (to around 800 degree C, i.e., about 1073 K), which supplies enough thermal energy for spin-flipping to occur, or

2. Passed through an electric discharge, or

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