Hydrofluogermanic Acid, H₂GeF₆

Hydrofluogermanic Acid, H₂GeF₆, is formed in solution in an analogous way to H₂SiF₆, i.e. by passing the vapour of the tetrafluoride into water:

3GeF₄ + 2H₂O = 2H₂GeF₆ + GeO₂.

The reaction differs, however, from the analogous reaction of silicon tetrafluoride, because the hydrated germanic oxide formed remains in solution. The addition of potash to the solution produces potassium germanifluoride, whilst excess of ammonia precipitates the oxide.