A 25.00 mL sample of 1.00 M CH3CO2H is titrated with 1.00 M NaOH. Calculate the pH after 30.00 mL of NaOH has been added. (Ka = 1.8 x 10^-5) (a) 6.90 (b) 9.36 (c) 11.54 (d) 12.95

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

검증된 단계별 안내

Calculate the initial moles of CH3CO2H using the formula: moles = concentration \( \times \) volume. Here, the concentration is 1.00 M and the volume is 25.00 mL.

Calculate the moles of NaOH added using the same formula: moles = concentration \( \times \) volume. The concentration is 1.00 M and the volume is 30.00 mL.

Determine the limiting reactant by comparing the initial moles of CH3CO2H and the moles of NaOH added. Since NaOH is in excess, calculate the moles of NaOH remaining after the reaction.

Use the Henderson-Hasselbalch equation to find the pH of the solution. The equation is: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \( \text{pKa} = -\log(\text{Ka}) \).

Substitute the concentrations of the acetate ion \([\text{A}^-]\) and acetic acid \([\text{HA}]\) into the Henderson-Hasselbalch equation to calculate the pH.

주요 개념

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

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, and understanding this change is crucial for calculating the final pH.

Buffer Solutions

Buffer solutions are mixtures that can resist changes in pH upon the addition of small amounts of acid or base. They typically consist of a weak acid and its conjugate base or a weak base and its conjugate acid. In the context of the titration of acetic acid (CH3CO2H) with NaOH, the solution will initially act as a buffer, maintaining a relatively stable pH until the equivalence point is approached.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation is a mathematical 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 problems, as it allows for the determination of pH at various points in the titration process, especially before and after the equivalence point.