Rubidium fluoride, RbF

The Rubidium fluoride, RbF, is obtained in anhydrous crystals by concentrating a solution of sodium carbonate neutralized with hydrofluoric acid. Its melting-point is given as 753° C. and 775° C. The boiling-point is 1410° C., and the vapour-pressure in atmospheres is given by the expression

log p = -40000/4.57T+5.243.

It is very soluble in water, its heat of solution being 5.80 Cal. Two hydrates are known, 2RbF,3H₂O, which melts at 36° C., and RbF,3H₂O. They are very hygroscopic. With hydrogen fluoride the fluoride yields the primary salt RbF,HF. Other acid fluorides, RbF,2HF, and RbF,3HF, have also been prepared.