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2001
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In the Laboratory
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An Easy and Versatile Experiment to Demonstrate Solvent Polarity Using Solvatochromic Dyes
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Clodoaldo Machado
Departamento de Química, Universidade Regional de Blumenau, FURB, CP 1507, Blumenau, SC 89010-971, Brazil
Vanderlei Gageiro Machado
Departamento de Química, Universidade Federal do Paraná, UFPR, CP 19081, Curitiba, PR 81531-990, Brazil
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May 2001
Vol. 78 No. 5
p. 649
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| Abstract |
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In this easy and versatile experiment, undergraduate students of experimental physical chemistry can discuss the concept of media polarity on the basis of the solvatochromic approach. Two solvatochromic dyes, Reichardt's betaine 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)-1-phenoxide and Brooker's merocyanine 4-[(1-methyl-4(1H)-pyridinylidene)ethylidene]-2,5-cyclohexadien-1-one were used to construct polarity scales for various solvents by means of visual observation and UV-vis spectroscopy. Changes in media polarity arising from mixed solvents or added electrolytes are also easily demonstrated. The data are used to justify kinetic and spectroscopic parameters.
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| Supplement |
A more detailed description of this experiment with examples of questions for discussion and sample student data sheets is available.
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 Contents |
JCE2001p0649W.doc (MS Word)
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| Download |
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| More Information |
Citation |
Machado, Clodoaldo; Machado, Vanderlei Gageiro. J. Chem. Educ. 2001 78 649.
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Keywords |
Demonstrations; Laboratory Instruction; Physical Chemistry; Solutions / Solvents; Theory/Practice; UV-Vis Spectroscopy
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History |
Created:
Last Updated: |
March 22, 2001
August 31, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
2001
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May
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649
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