Because the HBr dissociateds in solution. Be sure to show your work. A nano-sample contains 1 atom of potassium out of every 100 atoms. Standards are used to improve accuracy. They are necessary in volumetric analysis because it is difficult to make solutions with accurate concentrations and concentrations may change over time.
Standardization also minimizes errors due to end point detection and other systematic errors.
The equivalence point is where a stoichiometric amount of titrant has been added to the analyte. First, find pBr is at the start and at the equivalence point, and the volume titrant needed to reach the equivalence point.