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ERIC Number: EJ1090646
Record Type: Journal
Publication Date: 2016-Feb
Pages: 4
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0021-9584
Obtaining the Iodine Value of Various Oils via Bromination with Pyridinium Tribromide
Simurdiak, Michael; Olukoga, Olushola; Hedberg, Kirk
Journal of Chemical Education, v93 n2 p322-325 Feb 2016
A laboratory exercise was devised that allows students to rapidly and fairly accurately determine the iodine value of oleic acid. This method utilizes the addition of elemental bromine to the unsaturated bonds in oleic acid, due to bromine's relatively fast reaction rate compared to that of the traditional Wijs solution method. This method also uses pyridinium tribromide as a bromine source in an effort to eliminate many of the safety hazards of working with elemental bromine. After the addition of a known quantity of bromine to the reaction flask, excess bromine is reduced with potassium iodide forming elemental iodine. The elemental iodine is then titrated with sodium thiosulfate and a starch indicator in a back-titration to determine the amount of excess bromine added to the oleic acid. Students then determine the iodine value of oleic acid by using a 126 g iodine/80 g of bromine ratio. This exercise can yield results fairly close to the accepted iodine value of 90 for oleic acid, as several of the groups who tried out the experiment obtained iodine values close to 90. In addition, this exercise was also able to determine the iodine values of olive, coconut, and grapeseed oils. Finally, this experiment can be used to reinforce organic chemistry concepts as well as biochemistry concepts to IB Chemistry students.
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Descriptive; Guides - Classroom - Teacher
Education Level: Secondary Education; High Schools; Higher Education; Postsecondary Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A