#"Hydrogen bromide"# has a boiling point of #-66.8# #""^@C#. It is very soluble in water to give #"hydrobromic acid"#; and as with other gases, its solubility decreases with increasing temperature. The conc. #HBr(aq)# that you use in the lab, i.e. #"hydrobromic acid"#, is approx. 48% by weight, and approx. #9*mol*L^-1#.