Calculate The Ph of A 0.36 M Ch3coona Solution

Introduction

Sodium acetate (CH3COONa) is a weak base that dissociates in water to form acetate ions (CH3COO⁻) and sodium ions (Na⁺). The pH of a sodium acetate solution depends on its concentration and the dissociation constant of acetic acid (CH3COOH).

This calculator helps determine the pH of a 0.36 M sodium acetate solution using the Henderson-Hasselbalch equation.

Formula

The pH of a sodium acetate solution can be calculated using the Henderson-Hasselbalch equation:

Where:

• pKa is the acid dissociation constant of acetic acid (4.76 at 25°C)
• [CH3COO⁻] is the concentration of acetate ions
• [CH3COOH] is the concentration of acetic acid

For a sodium acetate solution, [CH3COO⁻] = [CH3COOH] because sodium acetate fully dissociates in water.

Calculation

Let's calculate the pH of a 0.36 M sodium acetate solution:

1. Identify the concentration of sodium acetate: 0.36 M
2. Since sodium acetate fully dissociates, [CH3COO⁻] = 0.36 M and [CH3COOH] = 0.36 M
3. Use the Henderson-Hasselbalch equation with pKa = 4.76:

The pH of a 0.36 M sodium acetate solution is 4.76.

Interpretation

A pH of 4.76 indicates that the solution is slightly acidic. This is expected because sodium acetate is a weak base that partially dissociates in water, forming acetic acid.

To verify this result, you can compare it with the pKa of acetic acid (4.76). When the ratio of [CH3COO⁻]/[CH3COOH] is 1, the pH equals the pKa, confirming our calculation.