The liquid,like water has a high dielectric constant (permittivity)and is weakly conducting. It is a good solvent for many inorganic and organic substances,to give conducting solutions. Substances which move the equilibria to the right when dissolved in hydrogen fluoride by taking up the fluoride ions,are acids. For example,boron trifluoride forms the tetrafluoroborate anion in a solution of hydrogen fluoride..............
However many substances notably alcohols have a greater proton affinity than the hydrogen fluoride molecule and so behave as bases for example etnanol..........
Even nitric acid will do this.........
Thus nitric acid behaves as a base in hydrogen fluoride. Hence increases of conductivity when substances dissolve in hydrogen fluoride may be due to acidic or basic behaviour........
The preparation and reactions of hydrogen halides.........
HYDROGEN FLUORIDE,ANHYDROUS HYDROFLUORIC ACID,HF...........
Hydrogen fluoride is the most important compound of fluorine. It is prepared in the laboratory,and on the large scale,by the reaction of calcium fluoride with concentrated sulphuric acid.......
The reaction is carried out in a lead retort;one suitable for the laboratory can be made from a piece of lead piping bent like a retort and closed at the shorter end. This is charged with fluorspar and the acid and heated and the hydrogen fluoride is distilled into a polythene vessel...........
Anhydrous hydrogen fluoride(as distinct from an aqueous solution of hydrofluoric acid) does not attack silica or glass. It reacts with metals to give fluorides.for example with heated iron the anhydrous iron(II)fluoride is formed;the same product is obtained by displacement of chlorine from iron(II)chloride:........