Consider the titration of a 35.0-mL sample of 0.175 M HBr with 0.200 M KOH. Determine each quantity. d. the pH at the equivalence point

Verified step by step guidance

1. Identify the type of titration: This is a strong acid (HBr) with a strong base (KOH) titration.
2. Determine the moles of HBr initially present using the formula: \( \text{moles} = \text{concentration} \times \text{volume} \).
3. Calculate the volume of KOH needed to reach the equivalence point using the stoichiometry of the reaction: \( \text{HBr} + \text{KOH} \rightarrow \text{KBr} + \text{H}_2\text{O} \).
4. At the equivalence point, all the HBr has reacted with KOH to form KBr and water. Since both are strong, the solution is neutral, and the pH is determined by the water, which is 7 at 25°C.
5. Conclude that the pH at the equivalence point for a strong acid-strong base titration is 7.

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 (a solution of known concentration) to a sample solution until the reaction reaches its equivalence point, where the amount of titrant equals the amount of substance in the sample. Understanding the stoichiometry of the reaction is crucial for calculating concentrations and pH at various points during the titration.

Equivalence Point

The equivalence point in a titration is the stage at which the amount of titrant added is stoichiometrically equivalent to the amount of substance present in the sample solution. At this point, the reaction between the acid and base is complete, and the pH of the solution can change dramatically. For strong acid-strong base titrations, the pH at the equivalence point is typically around 7, as the resulting solution contains only water and the salt formed from the neutralization.

pH Calculation

pH is a measure of the acidity or basicity of a solution, defined as the negative logarithm of the hydrogen ion concentration. At the equivalence point of a strong acid-strong base titration, the pH can be calculated based on the complete neutralization of the acid and base. In this case, since HBr is a strong acid and KOH is a strong base, the resulting solution will have a neutral pH of 7, assuming no other factors influence the pH.