Predicting evaporation rates and times for spills of chemical mixtures

Spreadsheet and short-cut methods have been developed for predicting evaporation rates and evaporation times for spills and constrained baths of chemical mixtures. Steady-state and time-varying predictions of evaporation rates can be made for six-component mixtures, including liquid-phase non-idealities as expressed through the UNIFAC method for activity coefficients. A group-contribution method is also used to estimate vapor-phase diffusion coefficients, which makes the method completely predictive. The predictions are estimates that require professional judgement in their application. One application that the evaporation time calculations suggest is a method for labeling chemical containers that allows one to quickly assess the time for complete evaporation of spills of both pure components and mixtures. The labeling would take the form of an evaporation time that depends on the local environment. For instance, evaporation time depends on indoor or outdoor conditions and the amount of each chemical among other parameters. This labeling would provide rapid information and an opportunity to premeditate a response before a spill occurs.