In the reaction between hydrogen and fluorine, hydrogen is being oxidized and fluorine is being reduced:
This reaction is spontaneous and releases 542 kJ per 2 g of hydrogen because the H-F bond is much stronger than the F-F bond. This reaction can be analyzed as two half-reactions. The oxidation reaction converts hydrogen to protons:
The reduction reaction converts fluorine to the fluoride anion:
The half reactions are combined so that the electrons cancel:
The protons and fluoride combine to form hydrogen fluoride in a non-redox reaction:
:2 H + 2 F → 2 HF
The overall reaction is: