Use Activity Calculator when you need to compute thermodynamic activity a = gamma * concentration. Enter Gamma coefficient and Concentration using the definitions and units below so the result can be reproduced.

Gamma coefficient

A finite measured or assumed value greater than or equal to 0.

Concentration

A finite measured or assumed value greater than or equal to 0, expressed in mol/L.

The published tool contract uses this rule: Compute thermodynamic activity a = gamma * concentration.

Activity

The calculated activity.

A ratio or percentage can conceal the scale of its numerator and denominator and becomes sensitive to measurement error when the denominator is small.

Retain the original Gamma coefficient and Concentration values and their units alongside the result. Activity Coefficient From Gamma Input is useful when you instead need to compute the ionic activity as the activity coefficient times the molar concentration. Activity From Fugacity provides another view by helping you compute the thermodynamic activity as the ratio of fugacity to the standard pressure of one bar.

• Activity Coefficient From Gamma Input

  Compute the ionic activity as the activity coefficient times the molar concentration.

• Activity From Fugacity

  Compute the thermodynamic activity as the ratio of fugacity to the standard pressure of one bar.

• Mean Ionic Activity

  Compute the mean ionic activity coefficient for a 1:1 electrolyte as the square root of the cation and anion coefficient product.