DebyeHückelFormeln

The Debye-Hückel formulas describe the behavior of electrolytes in dilute solutions. Developed by Peter Debye and Erich Hückel, these formulas provide a theoretical framework for understanding deviations from ideal behavior in ionic solutions. The primary concept is the formation of an "ionic atmosphere" around each ion. This atmosphere consists of oppositely charged ions that are attracted to the central ion, effectively screening its charge and reducing its activity.

The key Debye-Hückel equation relates the mean activity coefficient (γ±) of an ion to its charge and the ionic strength of the solution. The activity coefficient quantifies how the actual chemical potential of an ion deviates from its ideal value. In dilute solutions, the Debye-Hückel limiting law is often used, which assumes that the ions are point charges and that interionic interactions are primarily electrostatic. This law predicts that the activity coefficient decreases with increasing ionic strength.

For more concentrated solutions, the Debye-Hückel theory can be extended with additional terms to account for factors like the finite size of ions and solvation effects. These extended formulas, such as the Debye-Hückel equation with the ion-size parameter, offer a more accurate description of electrolyte behavior over a wider range of concentrations. The Debye-Hückel formulas are fundamental in physical chemistry and electrochemistry, enabling the calculation and prediction of properties like osmotic pressure and conductivity in electrolyte solutions.