Fluorine, F2, gas is the most reactive of all non-metals. Anhydrous liquid hydrogen fluoride, HF, can be electrolysed to produce F2 and hydrogen, H2, gases. Potassium fluoride, KF, is added to the liquid HF to increase electrical conductivity.
The equation for the reaction is
2HF(l) → F2(g) + H2(g)
F2 is used to make a range of chemicals, including sulfur hexafluoride, SF6, an excellent electrical insulator, and xenon difluoride, XeF2, a strong fluorinating agent.
The diagram below shows an electrolytic cell used to prepare F2 gas
Liquid HF, like water, is an excellent solvent for ionic compounds. In the same way that water molecules in an aqueous solution form the ions K+(aq) and F–(aq), when KF is dissolved in HF, the K+ and F– ions form ions that are written as K+ (HF) and F– (HF).
Write the equation for the half-reaction occurring at the anode.
(1 mark)