Calculate The Ph of 0.1 M Nh3

Introduction

Ammonia (NH3) is a weak base that dissociates in water to form ammonium ions (NH4+) and hydroxide ions (OH-). The pH of an ammonia solution can be calculated using the Henderson-Hasselbalch equation, which relates the pH to the concentration of the weak base and its conjugate acid.

This calculator helps you determine the pH of a 0.1 M ammonia solution at 25°C, considering the dissociation constant of ammonia (Kb = 1.8 × 10⁻⁵).

How to Calculate the pH of NH3

The pH of an ammonia solution can be calculated using the following steps:

1. Determine the concentration of ammonia (NH3) in moles per liter (M).
2. Use the dissociation constant of ammonia (Kb = 1.8 × 10⁻⁵ at 25°C).
3. Apply the Henderson-Hasselbalch equation for weak bases:

For a dilute solution, the concentration of NH4+ is approximately equal to the concentration of NH3, so the equation simplifies to:

Example Calculation

Let's calculate the pH of a 0.1 M ammonia solution:

1. Given: [NH3] = 0.1 M, Kb = 1.8 × 10⁻⁵
2. Calculate pKb: pKb = -log(Kb) = -log(1.8 × 10⁻⁵) ≈ 4.74
3. For a dilute solution, pH ≈ 14 + log(Kb) ≈ 14 + (-4.74) ≈ 9.26

Therefore, the pH of a 0.1 M ammonia solution is approximately 9.26.

Interpreting the Results

A pH of 9.26 indicates that the solution is basic, as expected for an ammonia solution. The pH increases as the concentration of ammonia increases, following the logarithmic relationship shown in the formula.

In practical applications, understanding the pH of ammonia solutions is important in chemical manufacturing, water treatment, and environmental science.