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.

검증된 단계별 안내

Step 1: Calculate the initial moles of propanoic acid (C2H5COOH) using the formula: moles = Molarity × Volume.

Step 2: For each volume of KOH added, calculate the moles of KOH added using the formula: moles = Molarity × Volume.

Step 3: Determine the moles of propanoic acid and its conjugate base (propanoate ion, C2H5COO-) after the reaction with KOH using stoichiometry.

Step 4: Use the Henderson-Hasselbalch equation to calculate the pH at each point where the buffer region is applicable: pH = pKa + log([A-]/[HA]).

Step 5: For the equivalence point and beyond, calculate the pH based on the concentration of the excess strong base (KOH) in the solution.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

20m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

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 the analyte (propanoic acid) until the reaction reaches its equivalence point, where the amount of titrant added is stoichiometrically equivalent to the amount of substance in the analyte.

pH and Acid-Base Neutralization

pH is a measure of the acidity or basicity of a solution, with lower values indicating acidic conditions and higher values indicating basic conditions. During a titration of a weak acid like propanoic acid with a strong base like KOH, the pH changes significantly, especially around the equivalence point, where the acid is completely neutralized, resulting in a sharp increase in pH.

Titration Curve

A titration curve is a graphical representation of the pH of a solution as a function of the volume of titrant added. It typically shows a gradual increase in pH at first, followed by a steep rise near the equivalence point, and then levels off. The shape of the curve provides insights into the strength of the acid and base involved, as well as the equivalence and half-equivalence points.