Tantalum Pentabromide, TaBr₅

Tantalum Pentabromide, TaBr₅, can be prepared either by distilling bromine on to powdered tantalum heated to between 260° and 300° C., or by passing bromine vapour over a heated mixture of freshly ignited tantalum pentoxide and sugar charcoal, all air being previously removed by means of carbon dioxide. The product is sublimed in an atmosphere of carbon dioxide to render it free from excess of bromine. The salt crystallises in long, yellow plates. The density of the sublimed material is 4.67. It melts at about 240° C. to a transparent, red liquid, and boils at about 320° C., giving a yellow vapour. When heated in hydrogen above its sublimation temperature, reduction to the metal and the lower bromides takes place. It fumes strongly in air, and is rapidly attacked by water, with precipitation of tantalic acid. Methyl and ethyl alcohols react with it readily, and with such considerable evolution of heat that they take fire.