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Olfactory Titration
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Abstract
The end point titration of sodium hydroxide with hydrochloric acid usually is signaled by phenolphthalein indicator that undergoes a color change from pink in the base to colorless in the acid. Thus, the student is able to detect, visually, completion of the neutralization reaction.
The purpose of this experiment is to use unique acid-base indicator--the odor of raw onion--to indicate the end point of the titration of sodium hydroxide with hydrochloric acid. The use of this novel indicator allows the student to detect the completion of the neutralization reaction by olfaction rather than by sight.
The experiment is conducted so that the student can initially discover which solution, sodium hydroxide or hydrochloric acid, eliminates the raw onion odor. As a result, the solution that "captures" the olfactory indicator is identified. The titration of this solution is carried out in the presence of both the visual and olfactory indicators so that the student can compare the times at which these two very different indicators signal the end point of the neutralization reaction.
Keywords (Audience):
High School / Introductory ChemistryKeywords (Domain):
Laboratory InstructionKeywords (Feature):
Filtrates and ResiduesKeywords (Pedagogy):
Hands-On Learning / ManipulativesKeywords (Subject):
Acids / BasesCiting Articles
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This article has been cited by 3 ACS Journal articles (3 most recent appear below).
Conductimetric Titrations: A Predict−Observe−Explain Activity for General Chemistry
K. Christopher Smith, Etinosa Edionwe, and Bayyinah MichelJournal of Chemical Education2010 87 (11), 1217-1221Conductimetric Titrations: A Predict−Observe−Explain Activity for General Chemistry
K. Christopher Smith, Etinosa Edionwe, and Bayyinah MichelJournal of Chemical Education2010 87 (11), 1217-1221A predict−observe−explain framework is used to explore conductimetric titrations of a hydrochloric acid−sodium hydroxide (strong acid−strong base) and an acetic acid−sodium hydroxide (weak acid−strong base) system in which all components are soluble. In ...
An Esterification Kinetics Experiment That Relies on the Sense of Smell
Deborah C. Bromfield-Lee and Maria T. Oliver-HoyoJournal of Chemical Education2009 86 (1), 82An Esterification Kinetics Experiment That Relies on the Sense of Smell
Deborah C. Bromfield-Lee and Maria T. Oliver-HoyoJournal of Chemical Education2009 86 (1), 82This experiment involves an esterification synthesis to study reaction kinetics where students explore these topics utilizing the sense of smell rather than the traditional approach of using spectroscopic methods. Students study the effects of various ...
A Closer Look at Acid–Base Olfactory Titrations
Kerry Neppel , Maria T. Oliver-Hoyo , Connie Queen and Nicole ReedJournal of Chemical Education2005 82 (4), 607A Closer Look at Acid–Base Olfactory Titrations
Kerry Neppel , Maria T. Oliver-Hoyo , Connie Queen and Nicole ReedJournal of Chemical Education2005 82 (4), 607This 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 ...
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- Received: August 03, 2009
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