Wha is the name of #HBr# (in water)?
The idea here is that we use two names for this compound, depending on which state we're dealing with.
When in the gaseous, liquid, or solid state, the compound is called hydrogen bromide. When it's dissolved in water, i.e. in the aqueous state, the compound is called hydrobromic acid.
You can get hydrobromic acid by dissolving gaseous hydrogen bromide in water.
#"HBr"_ ((g)) rightleftharpoons "HBr"_ ((aq))#
Hydrobromic acid is actually a very strong acid that dissociates completely in aqueous solution
#"HBr"_ ((aq)) + "H"_ 2"O"_ ((l)) -> "H"_ 3"O"_ ((aq))^(+) + "Br"_ ((aq))^(-)#