a program to calculate gas volumes fugacities and activities in the C-H-O system

CHO is a program which allows the user to derive molar volumes, fugacities and activities for H2O, CO2, CH4, H2 and CO and perform speciation calculations at fixed P, T and fO2 in the O-H and C-O-H systems. It uses the CORK equation of state (Holland & Powell 1991, CMP 109, 265-273) for all COH gases and additionally allows use of the Pitzer & Sterner equations (Pitzer & Sterner 1995, Int J Thermophys 16, 511-518) for H2O and CO2. For gas mixtures the program uses the Van Laar mixing model as outlined in Holland & Powell (2003, CMP 145, 492-501) but also allows this to be overridden in favour of ideal mixing.

The program opens with a main panel which allows the user 3 options:

1) Calculate molar volume or fugacity of individual gas species over a range in P and T

2) Calculate speciation in a gas mixture as a function of T at fixed fO2 and P or as a function of fO2 at fixed P and T. If the user specifies graphite presence the results will be in the COH system otherwise results will be calculated in the OH system

3) Calculate activity-composition relations for a pair of gases in a binary mixture of choice at fixed P and T


The executables, sample input files, and an info file explaining the use of the program are available here:

download: mac OSX version

download: Windows version

download: Linux version


** Updated Sept 2012

Last updated on 11-Sep-12 21:10