Title

Simple Method to Measure Ion Association in Strong Electrolyte Solutions

Presenter Information

Isaaac DiGennaro

Department

Chemistry

Major

Chemistry

Research Advisor

Gerald, Rex

Advisor's Department

Chemistry

Funding Source

Physical Chemistry Lab

Abstract

Debye-Hückel-Onsager theory (DHO) models molar conductivity as a function of ion concentration correcting for ionic effects. By Arrhenius theory, the ratio of predicted and measured molar conductivities shows the degree of association of the ions in solution. This experiment used deviation in molar conductivity from that predicted by DHO to calculate the dissociation constant for cupric sulfate solutions with concentrations < 0.01 M. A potential was applied to a cell with a DC power supply, and the potential difference was measured for various concentrations of electrolyte to obtain molar conductivities to compare to those predicted by DHO. Data showed a linear decrease in molar conductivity and dissociation with the square root of concentration. Near complete dissociation (91.6%) was observed at .3 mM ± 0.057%, decreasing to 57% at 6.9 mM ± 0.011%. Using a simple and inexpensive apparatus it was possible to demonstrate complex solution properties.

Biography

Isaac DiGennaro is a senior in chemistry, aiming to graduate in December 2015. The research presented here was performed as part of Chem 3429 Physical Chemistry Lab, as directed by Dr. Rex Gerald – NMR Technician. Isaac is interested in the overlap of biological and chemical processes, and hopes to pursue graduate studies to further his understanding of the field by participation in nutrition research.

Research Category

Sciences

Presentation Type

Poster Presentation

Document Type

Poster

Award

Sciences poster session, Third place

Location

Upper Atrium/Hall

Presentation Date

15 Apr 2015, 9:00 am - 11:45 am

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Apr 15th, 9:00 AM Apr 15th, 11:45 AM

Simple Method to Measure Ion Association in Strong Electrolyte Solutions

Upper Atrium/Hall

Debye-Hückel-Onsager theory (DHO) models molar conductivity as a function of ion concentration correcting for ionic effects. By Arrhenius theory, the ratio of predicted and measured molar conductivities shows the degree of association of the ions in solution. This experiment used deviation in molar conductivity from that predicted by DHO to calculate the dissociation constant for cupric sulfate solutions with concentrations < 0.01 M. A potential was applied to a cell with a DC power supply, and the potential difference was measured for various concentrations of electrolyte to obtain molar conductivities to compare to those predicted by DHO. Data showed a linear decrease in molar conductivity and dissociation with the square root of concentration. Near complete dissociation (91.6%) was observed at .3 mM ± 0.057%, decreasing to 57% at 6.9 mM ± 0.011%. Using a simple and inexpensive apparatus it was possible to demonstrate complex solution properties.