Calculate Ph of A Solution 0.5 M C2h5nh2 0.25m C2h5nh3cl

Introduction

This calculator determines the pH of a solution containing diethylamine (C2H5NH2) and its conjugate acid diethylammonium chloride (C2H5NH3Cl). The calculation uses the Henderson-Hasselbalch equation, which relates the pH of a buffer solution to the ratio of the concentrations of a weak acid and its conjugate base.

Diethylamine is a weak base that can accept a proton to form diethylammonium chloride. The pH of the solution depends on the ratio of these two species and the pKa of the weak base.

Calculation Method

The pH of the solution is calculated using the Henderson-Hasselbalch equation:

Where:

• [C2H5NH2] is the concentration of diethylamine (M)
• [C2H5NH3Cl] is the concentration of diethylammonium chloride (M)
• pKa is the acid dissociation constant of diethylammonium chloride (-log10 of the Ka value)

The pKa value for diethylammonium chloride is approximately 10.75 at 25°C.

Example Calculation

For a solution with [C2H5NH2] = 0.5 M and [C2H5NH3Cl] = 0.25 M:

The calculated pH is approximately 11.05.

Interpretation

A pH of 11.05 indicates a strongly basic solution. This is expected since diethylamine is a weak base that can donate protons to form diethylammonium chloride. The solution behaves as a buffer, maintaining a relatively stable pH despite the addition of small amounts of acid or base.

The ratio of [C2H5NH2] to [C2H5NH3Cl] determines the buffer capacity. A higher ratio of base to conjugate acid results in a higher pH, while a lower ratio results in a lower pH.