What is the concentration of an HBr solution if 12.0 mL of the solution is neutralized by 15.0 mL of a 0.25 M KOH solution?

The reaction between HBr and KOH is a 1:1 ratio. This means that the moles of HBr present in the solution will be equal to the moles of KOH used in the neutralization reaction. Using this information and the volume and concentration of KOH used, you can calculate the concentration of the HBr solution.