Radium Bromide, RaBr₂

Radium Bromide, RaBr₂, may be formed by the action of hydrobromic acid solution on the carbonate and subsequent crystallisation as the dihydrate, RaBr₂.2H₂O, isomorphous with barium bromide dihydrate. It gives up bromine on exposure to the air and becomes alkaline, forming the hydroxide and ultimately the carbonate.

Radium bromide is less volatile than barium bromide which volatilises at 820° C., and it is possible that a separation of the two might be effected by this method.

The molecular heat of formation of anhydrous radium bromide is probably about 180 Cal., and the heat of solution 2 Cal. It is more soluble in water than the chloride.

Measurements of the electrical conductivity of radium bromide solutions have been made. The mobility of ½Ra^• was found to be 58, and the temperature coefficient at 18° C. 0.024.

There is some evidence of the existence of the compound 2BaBr₂. RaBr₂.6H₂O.