Rubidium bromide is the bromide of rubidium. It has a NaCl crystal structure, with a lattice constant of 685 picometres. There are several methods for synthesising rubidium bromide. One involves reacting rubidium hydroxide with hydrobromic acid: RbOH + HBr → RbBr + H2O Another method is to neutralize rubidium carbonate with hydrobromic acid: Rb2CO3 + 2 HBr → 2 RbBr + H2O + CO2 Rubidium metal would react directly with bromine to form RbBr, but this is not a sensible production method, since rubidium metal is substantially more expensive than the carbonate or hydroxide; moreover, the reaction would be explosive. References WebElements. URL accessed March 1, 2006. Rubidium compounds Bromides Metal halides Alkali metal bromides Rock salt crystal structure