A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: 5 mL.

Verified step by step guidance

Determine the initial moles of propanoic acid (C2H5COOH) using the formula: \( \text{moles} = \text{concentration} \times \text{volume} \).

Calculate the moles of KOH added using the formula: \( \text{moles} = \text{concentration} \times \text{volume} \).

Determine the moles of propanoic acid that react with KOH, considering the stoichiometry of the reaction: \( \text{C2H5COOH} + \text{KOH} \rightarrow \text{C2H5COOK} + \text{H2O} \).

Calculate the moles of propanoic acid and its conjugate base (propanoate ion, C2H5COO-) remaining after the reaction.

Use the Henderson-Hasselbalch equation to find the pH: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{C2H5COO-}]}{[\text{C2H5COOH}]} \right) \), where \( \text{pKa} \) is the acid dissociation constant of propanoic acid.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Titration

An acid-base titration is a quantitative analytical method used to determine the concentration of an acid or base in a solution. In this process, a solution of known concentration (the titrant) is added to a solution of unknown concentration until the reaction reaches its equivalence point, where the amount of acid equals the amount of base. The pH changes during the titration can be monitored to determine the endpoint.

Weak Acid and Strong Base Reaction

In this titration, propanoic acid (a weak acid) reacts with potassium hydroxide (a strong base). The weak acid does not fully dissociate in solution, which affects the pH at various points during the titration. The resulting solution will have a pH that is influenced by the remaining weak acid and the produced salt, as well as the strong base added.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation is a formula used to calculate the pH of a buffer solution. It relates the pH to the pKa of the weak acid and the ratio of the concentrations of the conjugate base to the weak acid. This equation is particularly useful in titration scenarios to determine the pH at points before, at, and after the equivalence point, especially when dealing with weak acids and their conjugate bases.

Recommended video:

Guided course

02:40

Henderson-Hasselbalch Equation

Related Practice

Textbook Question

Consider the titration of a 20.0-mL sample of 0.105 M HC₂H₃O₂ with 0.125 M NaOH. Determine each quantity. b. the volume of added base required to reach the equivalence point

Textbook Question

A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: 0 mL, 5 mL, 10 mL, equivalence point, one-half equivalence point, 20 mL, 25 mL. Sketch the titration curve.

Textbook Question

A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: 0 mL.

Textbook Question

A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: 10 mL.

Textbook Question

A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: equivalence point.

Textbook Question

A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. Calculate the pH at each volume of added base: one-half equivalence point.