F2 being a strong oxidising agent oxidises H2O to O2 or O3. The reactions are given as:
2F2(g) + 2H2O(l) → 4H+(aq) + 4F–(aq) + O2(g)
3F2(g) + 3H2O(l) → 6H+(aq) + 6F–(aq) + O3(g)
Cl2 on the other hand, reacts with H2O to form hydrochloric acid and hypochlorous acid as per the following equation: