Rubidium carbonate, Rb₂CO₃

The Rubidium carbonate, Rb₂CO₃, is prepared in the anhydrous state by ignition of the residue from the evaporation of a solution of rubidium hydroxide and ammonium carbonate. It melts about 837° C., and its specific heat is 0.123 between 18° and 47° C. It is very deliquescent, the heat of solution in water being 9.077 Cal. The solution is alkaline. Several hydrates have been described. The heat of formation of the anhydrous salt from its elements is 274.9 Cal.