The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 15
(2010) pp 281-284
Applying Psuedo-First-Order Methodology to Study Ni-PADA Ligand Substitution with Ammonia: A Laboratory Experiment
Timothy L. Sorey*, Anthony Diaz, and Terry A. Helland
Central Washington University, Department of Chemistry,
E. University Way, Ellensburg, WA, 98926-7539, SoreyT@cwu.EDU
Published: 31 July 2010
Abstract. This physical/inorganic chemistry laboratory experiment introduces metal-ligand substitution reactions and spectroscopic determination of forward and reverse rate constants. First, students study various forward and reverse rate constants of reversible first order reactions by applying mathematical models in EXCEL. Then, students apply pseudo first order methodology, reacting excess ammonia with aqueous Ni(II)-pyridine-2-azo-p-dimethylaniline in the formation of hexaaminenickel(II) ion. Using a MicroLAB FS-522 16 wavelength spectrometer, students acquire and analyze data to solve for Ni(II)-PADA and PADA concentrations. Finally, students apply EXCEL SOLVER in determination of forward and reverse rate constants. This guided-inquiry lab was performed in an integrated senior level physical-inorganic chemistry lab.
Key Words: Laboratories and Demonstrations; physical chemistry; ligand substitution reaction; spectroscopy; math modeling; micro-computer-based lab; Ni-PADA complex; EXCEL and SOLVER add-in
(*) Corresponding author. (E-mail: SoreyT@cwu.EDU)
Supporting Materials:An expanded version of experimental procedures for the students, notes for the instructor, and sample student data are available (367 KB).