Activity Coefficient Calculator
Calculate activity coefficients using Debye-Huckel limiting law, extended Debye-Huckel, and Davies equation.
Ion Parameters
Activity Coefficient (Extended DH)
0.753771
Debye-Huckel Extended Law:
log(gamma) = -A * z^2 * sqrt(I) / (1 + B * a * sqrt(I))
Where A = 0.509, B = 0.328, a = ion radius (A), I = ionic strength
Davies Equation:
log(gamma) = -A * z^2 * (sqrt(I)/(1+sqrt(I)) - 0.3*I)
Valid for ionic strengths up to 0.5 mol/kg
Understanding Activity Coefficients
Activity coefficients account for the non-ideal behavior of ions in solution. In an ideal solution, activity equals concentration, but real solutions deviate from this due to electrostatic interactions between ions. The activity coefficient (gamma) relates activity to concentration: a = gamma * C. Values less than 1 indicate that ions are less reactive than their concentration suggests.
Methods Comparison
Limiting Law
Simple approximation valid for I < 0.01 mol/kg
Extended DH
Accounts for ion size, valid for I < 0.1 mol/kg
Davies
Empirical extension, valid for I < 0.5 mol/kg