Step 1
In a titration, the next equation is used in the equivalence point:
![M1\text{ x V1 = M2 x V2}](https://img.qammunity.org/2023/formulas/chemistry/college/bk0oe2r5ezkizqfhxb0gaujrys8rvfldke.png)
Where,
Number 1 will the conditions of HBr
Number 2 will the conditions of Ca(OH)2
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Step 2
Information provided:
M1 = 0.0105 M
V1 = unknown
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M2 = 0.0100 M
V2 = 125 mL
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Step 3
Procedure:
From step 1, V1 is found as follows:
![\begin{gathered} M1\text{ x V1 = M2 x V2} \\ V1\text{ = }\frac{M2\text{ x V2}}{M1} \\ V1\text{ = }\frac{0.0100\text{ M x 125 mL}}{0.0105\text{ M}}=\text{ 119 mL} \end{gathered}](https://img.qammunity.org/2023/formulas/chemistry/high-school/6nrrm1s0ewacaj9qkerk5e2tsykim0d3vv.png)
Answer: V1 = 119 mL