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The Pitzer model

The Pitzer model can be used to calculate various solution properties for a fixed composition.

All examples use the import convention:

import pytzer as pz

Arguments

All the main Pitzer model functions have the same syntax, for example:

Gibbs_nRT = pz.Gibbs_nRT(solutes, temperature, pressure)

  • The argument solutes is an dict containing the molality (in mol/kg) of each solute in the solution. Each molality must be a scalar float.

  • Temperature is a scalar float in kelvin (K).

  • Pressure is a scalar float in decibar (dbar). It should include atmospheric pressure.

The result is always either a scalar float or a dict of scalar floats with the same keys as in the solutes.

Functions

The properties that can be calculated using the syntax above are:

Excess Gibbs energy

Excess Gibbs energy of the solution.

Gibbs_nRT = pz.Gibbs_nRT(solutes, temperature, pressure)

Solute activity coefficients

Chemical activity coefficients for every solute or their natural logarithms.

activity_coefficients = pz.activity_coefficients(solutes, temperature, pressure)
log_activity_coefficients = pz.log_activity_coefficients(solutes, temperature, pressure)

Water activity

Chemical activity of the solvent (water) or its natural logarithm.

activity_water = pz.activity_water(solutes, temperature, pressure)
log_activity_water = pz.log_activity_water(solutes, temperature, pressure)

Osmotic coefficient

Osmotic coefficient of the solution.

osmotic_coefficient = pz.osmotic_coefficient(solutes, temperature, pressure)