Presentation Title

A New Approach to Binary Phase Diagrams

Start Date

November 2016

End Date

November 2016

Location

HUB 302-85

Type of Presentation

Poster

Abstract

Single compound phase diagrams are plots that map the pressures and temperatures where two phases are in equilibrium. When two compounds are mixed together, a third axis representing composition is used to depict phase transitions. Due to the increased complexity of these systems, binary phase diagrams are traditionally represented in a piecemeal fashion to students. This obscures the relationship of related properties. The goal of this work is to write an undergraduate physical chemistry laboratory experiment that has student collect both boiling and freezing curves of a system with several complex features and plot a complete binary phase diagram. The system introduced for this experiment is composed of cyclohexane and tert-butanol, which were chosen for their miscibility, ability to form azeotrope and eutectic compositions, low boiling and high melting points, and low toxicity compared to one of the most common systems used for similar laboratories: cyclohexanone and tetrachloroethylene, the former being very caustic and the latter being carcinogenic. Through the development of the experiment, we were able to create a simple, yet precise, procedure for collecting both the vapor and liquid states of substances at equilibrium, which is especially useful for determining the azeotrope composition of a binary system.

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Nov 12th, 1:00 PM Nov 12th, 2:00 PM

A New Approach to Binary Phase Diagrams

HUB 302-85

Single compound phase diagrams are plots that map the pressures and temperatures where two phases are in equilibrium. When two compounds are mixed together, a third axis representing composition is used to depict phase transitions. Due to the increased complexity of these systems, binary phase diagrams are traditionally represented in a piecemeal fashion to students. This obscures the relationship of related properties. The goal of this work is to write an undergraduate physical chemistry laboratory experiment that has student collect both boiling and freezing curves of a system with several complex features and plot a complete binary phase diagram. The system introduced for this experiment is composed of cyclohexane and tert-butanol, which were chosen for their miscibility, ability to form azeotrope and eutectic compositions, low boiling and high melting points, and low toxicity compared to one of the most common systems used for similar laboratories: cyclohexanone and tetrachloroethylene, the former being very caustic and the latter being carcinogenic. Through the development of the experiment, we were able to create a simple, yet precise, procedure for collecting both the vapor and liquid states of substances at equilibrium, which is especially useful for determining the azeotrope composition of a binary system.