Debye-Hückel Limiting Law

Introduction to Debye-Hückel Limiting Law

The Debye-Hückel Limiting Law predicts the mean activity coefficient (γ±) of an electrolyte in solution at low concentration. It's particularly important for understanding ionic interactions in solutions. The formula includes the ionic strength (I) of the solution and charges of the ions (Z+ and Z-). A constant value (A) for water at 25 °C is typically used, where A = 0.5092, hence the coefficient 0.5092 in the function. The activity coefficients are relevant for adjusting concentrations to account for non-ideal behavior.

Parameter usage:

• ionicStrength = the ionic strength of the solution
• chargeA= charge of the cation
• chargeB= charge of the anion

Example valid values:

• ionicStrength= 0.1 M
• chargeA= 1 (for Na+)
• chargeB= -1 (for Cl-)

Data validation

Drinkable water should have a ionic strength value greater than zero and ion charges should not be zero.

Summary

This limit law applies broadly within chemistry for calculating the activity coefficient of ions in a solution at low ionic strength.