Waiting
Login-Verarbeitung ...

Trial ends in Request Full Access Tell Your Colleague About Jove

2.8: Acid–Base Equilibria: Activity-Based Definition of pH

TABLE OF
CONTENTS
JoVE Core
Analytical Chemistry

Ein Abonnement für JoVE ist erforderlich, um diesen Inhalt ansehen zu können. Melden Sie sich an oder starten Sie Ihre kostenlose Testversion.

Education
Acid–Base Equilibria: Activity-Based Definition of pH
 
TRANSCRIPT

2.8: Acid–Base Equilibria: Activity-Based Definition of pH

For an ideal solution, the pH is defined as the negative logarithm of the hydrogen ion concentration. For a non-ideal solution, an accurate measurement of the pH must consider the negative logarithm of the hydrogen ion activity rather than concentration. In such a solution, the pH can be more accurately defined as the negative logarithm of a product of the hydrogen ion concentration and its activity coefficient.

In solutions of very low ionic strength—for example, pure water—the activity coefficient of the hydrogen ion is close to one when the ionic strength of the solution increases due to the addition of an electrolyte that does not donate or accept a proton. This results in a slight decrease in the pH of the solution. In other words, the addition of an electrolyte increases the hydrogen ion activity, or the effective hydrogen ion concentration in the solution, which decreases the pH of the solution.

Tags

Keywords: Acid-base Equilibria PH Hydrogen Ion Concentration Hydrogen Ion Activity Activity Coefficient Ionic Strength Electrolyte

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter