Consider the titration of a 35.0-mL sample of 0.175 M HBr with 0.200 M KOH. Determine each quantity. e. the pH after adding 5.0 mL of base beyond the equivalence point

Verified step by step guidance

1. Calculate the initial moles of HBr using the formula: \( \text{moles of HBr} = M \times V \), where \( M \) is the molarity and \( V \) is the volume in liters.
2. Calculate the moles of KOH added at the equivalence point using the formula: \( \text{moles of KOH} = M \times V \), where \( M \) is the molarity and \( V \) is the volume in liters.
3. Determine the moles of KOH added beyond the equivalence point by calculating the moles in the additional 5.0 mL of KOH.
4. Calculate the excess moles of KOH by subtracting the initial moles of HBr from the total moles of KOH added.
5. Determine the pH by calculating the concentration of excess OH\(^-\) ions in the solution and using the formula: \( \text{pOH} = -\log[\text{OH}^-] \), then convert to pH using \( \text{pH} = 14 - \text{pOH} \).

Key Concepts

Titration

Titration is a quantitative analytical technique used to determine the concentration of a solute in a solution. It involves the gradual addition of a titrant (in this case, KOH) to a solution of analyte (HBr) until the reaction reaches its equivalence point, where stoichiometrically equivalent amounts of acid and base have reacted. Understanding the titration process is essential for calculating pH changes at various stages.

Equivalence Point

The equivalence point in a titration is the stage at which the amount of titrant added is exactly enough to completely neutralize the analyte solution. For strong acid-strong base titrations, the pH at the equivalence point is typically around 7.0. Knowing the equivalence point helps in determining how much base has reacted with the acid and what the resulting pH will be after additional base is added.

pH Calculation

pH is a measure of the acidity or basicity of a solution, calculated as the negative logarithm of the hydrogen ion concentration. After the equivalence point in a titration of a strong acid with a strong base, the solution becomes basic, and the pH can be calculated using the concentration of excess hydroxide ions from the added base. Understanding how to calculate pH in these scenarios is crucial for determining the solution's properties after titration.