Simple Method to Measure Ion Association in Strong Electrolyte Solutions
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
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.
