Final answer:
The concentration of the HBr solution is approximately 0.3125 M.
Step-by-step explanation:
To find the concentration of the HBr solution, we can use the equation:
M1V1 = M2V2
where M1 is the concentration of the KOH solution (given as 0.25 M), V1 is the volume of the KOH solution (given as 15.0 mL), M2 is the concentration of the HBr solution (what we're trying to find), and V2 is the volume of the HBr solution (given as 12.0 mL).
Plugging in the values:
(0.25 M)(15.0 mL) = M2(12.0 mL)
Simplifying:
3.75 = 12M2
Dividing both sides by 12:
M2 = 3.75/12 ≈ 0.3125 M
Therefore, the concentration of the HBr solution is approximately 0.3125 M.