Microsoft EXCEL spreadsheet-based program for calculating equilibrium gas speciation in the C-O-H-S-Cl-F system

摘要

A high-temperature gas is a relatively simple mixture of gas species in homogeneous equilibrium. Volcanic gases are composed of the elements C, O, H, S, Cl and F along with trace amounts of other components. We present an Microsoft EXCEL spread sheet and add-in for calculation of homogeneous equilibrium in this system. This EXCEL extension allows users to calculate equilibrium species fugacities at 1 bar for any volcanic or laboratory gas mixture in the C-O--H-S-Cl-F system. Homogeneous equilibrium is calculated using the RAND algorithm based on the assumption of ideal mixing of 66 molecular gas species. This is implemented as a hierarchy of class objects written in C++. This computation engine is compiled into a dynamically linked EXCEL add-in which can be accessed by any EXCEL spread sheet. An easy to use spread sheet is provided which implements this add-in.