객관식
Complete neutralization of 12.5 mL of Sr(OH)₂ requires 36 mL of 0.1 M HCl. What is the concentration of the Sr(OH)₂ solution?
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18. Aqueous Equilibrium
Acid-Base Indicators
객관식
Which of the following indicators is most suitable for use in the titration of hypobromous acid (HBrO, pKa=8.7) with a strong base?
A
Bromothymol blue (pH range: 6.0-7.6)
B
Methyl orange (pH range: 3.1-4.4)
C
Phenolphthalein (pH range: 8.2-10.0)
D
Litmus (pH range: 4.5-8.3)
검증된 단계별 안내1
Identify the type of titration: This is a weak acid (hypobromous acid) being titrated with a strong base.
Determine the pH at the equivalence point: For a weak acid-strong base titration, the pH at the equivalence point is greater than 7. The pH can be estimated using the formula: \( \text{pH} = \frac{1}{2} (\text{pKa} + \text{pKw}) \), where \( \text{pKw} = 14 \).
Calculate the approximate pH at the equivalence point: Substitute the given \( \text{pKa} = 8.7 \) into the formula to find the pH at the equivalence point.
Select an appropriate indicator: The indicator should change color at a pH close to the equivalence point. Compare the pH ranges of the given indicators to the calculated pH.
Choose the indicator with a pH range that includes the equivalence point pH: Phenolphthalein, with a pH range of 8.2-10.0, is suitable as it encompasses the calculated equivalence point pH.
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