Answer:
[tex]\large \boxed{\text{7.65 mL}}[/tex]
Explanation:
1. Balanced chemical equation.
[tex]\rm HBr + KOH \longrightarrow KBr + H_{2}O[/tex]
2. Moles of NaOH
[tex]\text{Moles of NaOH} =\text{ 18.8 mL NaOH} \times \dfrac{\text{0.129 mmol NaOH }}{\text{1 mL NaOH }} = \text{2.425 mmol NaOH }[/tex]
3. Moles of HBr
The molar ratio is 1 mmol HBr:1 mmol NaOH
[tex]\text{Moles of HBr}= \text{2.425 mmol NaOH} \times \dfrac{\text{1 mmol HBr}}{\text{1 mmol NaOH}} =\text{2.425 mmol HBr}[/tex]
4. Volume of HBr
[tex]V = \text{2.425 mmol HBr}\times \dfrac{\text{1mL HBr}}{\text{0.317 mmol HBr}} = \textbf{7.65 mL HBr}\\\\\text{The reaction requires $\large \boxed{\textbf{7.65 mL HBr}}$}[/tex]