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2005
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In the Laboratory
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A Closer Look at Acid–Base Olfactory Titrations
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Kerry Neppel, Maria T. Oliver-Hoyo, Connie Queen, and Nicole Reed
Department of Chemistry, North Carolina State University, Raleigh, NC 27695
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April 2005
Vol. 82 No. 4
p. 607
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| Abstract |
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This laboratory experiment uses the sense of smell to determine end points of acid–base titrations. Olfactory indicators include garlic, onions, and vanillin. Results show that garlic and vanillin gave the most accurate results when calculated NaOH molarities were compared to the standardized values. These olfactory indicators in acid–base titrations gave consistent results when tested by a diverse student population. The preparation times, cost, and safety issues are comparable to traditional titration experiments. In addition to olfactory determinations, the intrinsic pigments in yellow and red onions were tested as complementary visual indicators and compared to commercial indicators added to white onion solutions. All students, including those with visual impairments, may perform these olfactory titrations and the level of instruction can be expanded from a phenomenological point to the complex aroma chemistry behind the scenes. These experiments can also educate the nondisabled student and change attitudes toward disabled partners.
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| Supplement |
Page 13 in SM is blank.
Experimental protocols for the students using different types of olfactory indicators and notes for the instructors are available.
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 Contents |
JCE2005p0607W.doc (Microsoft Word)
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| More Information |
Citation |
Neppel, Kerry; Oliver-Hoyo, Maria T.; Queen, Connie; Reed, Nicole. J. Chem. Educ. 2005 82 607.
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Keywords |
Acid–Base Chemistry; General Chemistry; Quantitative Analysis
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History |
Created:
Last Updated: |
March 4, 2005
March 14, 2005
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