Ternary Diagram Basics

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Ternary Phase Diagrams |

Investigation to determine the binodal curve and typical tie lines of ethyl acetate, water and propionic acid ternary phase diagram |

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Jamie Steel |

4/13/2013 |

This report presents the use of ternary diagrams to determine the compositions of aqueous and organic phases within a water-ethyl acetate-propionic acid mixture of known overall composition. The binodal curve was plotted using titrations of propionic acid into known water-ethyl acetate mixtures. The tie lines were then plotted making use of the aforementioned curve and weight ratios obtained from the volume of each phase and a digital densitometer. The plotted points for the binodal curve were found to contain more propionic acid than the theoretical values. This was likely due to slight inaccuracies in determining the point at which the phases had merged. The practical applications were also demonstrated using the diagram to determine the number of stages required for a separation of significant purity. |

Introduction

Due to the properties of propionic acid, it is completely miscible in both water and ethyl acetate. However water and ethyl acetate are only partially miscible in each other so when a large mass fraction of propionic acid is present, resulting in low mass fractions of water and ethyl acetate, two phases start to form which are immiscible in each other. The composition of these phases in entirely dependent on the original composition of the mixture, providing a constant temperature and pressure is present.

The objective of the experiment is to determine the location of the binodal curve and use it to obtain the allocation of the components in mixtures of known overall compositions.

In order to plot the binodal curve, several known compositions of water and ethyl acetate will be produced. These mixtures will form two phases and as a result will create an appearance of turbidity. Then propionic acid is titrated in to the mixture until the...