Calculate Ph of 0.10m C4h9nh2 Measured at 12.04

This guide explains how to calculate the pH of a 0.10M butylamine (C4H9NH2) solution at 12.04°C using the Henderson-Hasselbalch equation. We'll cover the formula, assumptions, and practical applications of this calculation in chemistry.

Introduction

Butylamine (C4H9NH2) is a weak organic base that dissociates in water to form the butylammonium ion (C4H9NH3+). The pH of a solution containing this base can be calculated using the Henderson-Hasselbalch equation, which relates the pH to the concentration of the base and its conjugate acid.

This calculation is important in chemical analysis, environmental science, and industrial applications where precise pH measurements are required.

pH Calculation Formula

The pH of a weak base solution can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log₁₀([Base]/[Conjugate Acid])

Where:

pKa is the acid dissociation constant of the conjugate acid (for butylammonium ion, pKa ≈ 10.65 at 25°C)
[Base] is the concentration of the undissociated base (C4H9NH2)
[Conjugate Acid] is the concentration of the dissociated form (C4H9NH3+)

Note: The pKa value may vary slightly with temperature. For this calculation, we use the value at 12.04°C, which is approximately 10.60.

Worked Example

Let's calculate the pH of a 0.10M butylamine solution at 12.04°C:

Example Calculation

Given:

Concentration of C4H9NH2 (Base) = 0.10 M
pKa of C4H9NH3+ at 12.04°C = 10.60

Assuming complete dissociation (which is reasonable for weak bases at this concentration):

[Base] = 0.10 M
[Conjugate Acid] = 0.10 M

Applying the Henderson-Hasselbalch equation:

pH = 10.60 + log₁₀(0.10/0.10) = 10.60 + log₁₀(1) = 10.60 + 0 = 10.60

The calculated pH is 10.60.

Interpreting Results

The pH of 10.60 indicates that the solution is basic, which is expected for a weak base like butylamine. This means the solution contains more OH- ions than H+ ions.

Comparison table of pH ranges:

pH Range	Solution Type
0-6	Acidic
7	Neutral
8-14	Basic

Frequently Asked Questions

What is the pKa of butylammonium ion at 12.04°C?: The pKa of butylammonium ion (C4H9NH3+) at 12.04°C is approximately 10.60. This value is used in the Henderson-Hasselbalch equation for pH calculations.
Can I use this calculator for other weak bases?: This calculator is specifically designed for butylamine (C4H9NH2). For other weak bases, you would need to adjust the pKa value according to the specific compound's properties.
What assumptions are made in this calculation?: The calculation assumes complete dissociation of the weak base and uses the pKa value at 12.04°C. For more precise results, experimental pKa values should be used.
How does temperature affect the pH calculation?: Temperature affects the pKa value. The pKa of butylammonium ion decreases slightly as temperature increases. For accurate results, use the pKa value specific to your measurement temperature.