Qualitative and Multi-Element Quantitative Flame-Emission Analysis of Group IA and Group IIa Elements Using a Flame Photometer, a Fiber-Optic Probe, and a Spectrometer

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 11 Issue 1 (2006) pp 41-44

Qualitative and Multi-Element Quantitative Flame-Emission Analysis of Group IA and Group IIa Elements Using a Flame Photometer, a Fiber-Optic Probe, and a Spectrometer

Frazier W. Nyasulu,* William Cusworth III, Jon Weiner, and John Macklin

Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195, nyasulu@chem.washington.edu
Received August 2, 2005. Accepted November 23, 2005.

Published online: 23 January 2006

Abstract. This manuscript describes the use of a flame photometer, a fiber-optic probe, and a spectrometer to reliably record the emission spectra (wavelength and intensity) of Li⁺, Na⁺, K⁺, Ca²⁺, and Sr²⁺ solutions. The setup removes the problems of transient short-lived emissions observed with Bunsen burner flames. Students are able to establish the uniqueness of each element’s emission spectra as well as determine the concentrations of all five metal ions in a single sample. Because the third most intense Sr²⁺ peak at 670.3 nm matches the Li⁺ single emission, students perform two different procedures in order to determine Li⁺ in the presence of Sr²⁺. In one procedure, the intensity expected from the Sr²⁺ is subtracted and in the other procedure the Sr²⁺ is precipitated as SrSO₄ using Fe(II)(NH₄)₂(SO₄)₂^·6H₂O (s). We also have students determine the concentrations of these ions in Gatorade.

Key Words: Laboratories and Demonstrations; general chemistry; quantitative analysis; atomic spectroscopy

(*) Corresponding author. (E-mail: nyasulu@chem.washington.edu)

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Supporting Materials:

The laboratory documentation and the excel file used for the calculations are included in a Zip file (362 KB).