Inconsistent implementation of chemical potentials and partial molar entropies in IdealMolalSoln

[speth]

Problem description

Steps to reproduce

>>> import cantera as ct
>>> p = ct.Solution('test/data/thermo-models.yaml', 'ideal-molal-aqueous')
>>> p.chemical_potentials
array([-38968574.59879851, -44670331.92380941, -47654928.77054328,
       -50378341.42634466])
>>> p.partial_molar_enthalpies - p.T * p.partial_molar_entropies
array([-1.09382545e+04, -5.71269558e+06, -8.69729243e+06, -1.14207051e+07])
>>> p.gibbs_mole
-38985553.501734525
>>> p.enthalpy_mole - p.T * p.entropy_mole
-27917.15745574266

Behavior

The two pairs of printed quantities should be equal, by the identity μ_k = h_k - T·s_k.

The displayed information comes from the implementations of getChemPotentials and getPartialMolarEnthalpies in the IdealMolalSoln class (YAML model name ideal-molal-solution). These two methods are used in the calculation of gibbs_mole and entropy_mole for this phase type, so the second error follows directly from the first.

System information

• Cantera version: 2.6.0 or main at 8fbb4bc

Attachments

Additional context

This was discovered as part of #1299, which implements Cantera/enhancements#114.