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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 24 (2019) pp 71-74

Roses are Red, Violets are Blue, Unless Exposed to SO₂: Using Natural Flowers as Colorful Sulfur Dioxide Detectors

Jeffrey J. Rosentreter* and Preston Hymas

Department of Chemistry, Idaho State University, Pocatello, ID, rosejeff@isu.edu
Received November 15, 2018. Accepted March 13, 2019.

Published: 23 April 2019

Abstract. Without question, the use of both natural products and colorful visuals can spark interest and provide a high degree of student engagement. The same chemicals naturally developed in plants to attract animals continue to ignite interest and delight scientists and students alike. In this paper, anthocyanins—natural pigmenting compounds produced by plants that provide many of the brilliant colors of fruits and flowers—will form the basis of a classroom experiment which provides an engagingly visual means of detecting atmospheric sulfur dioxide gas. These aromatic carbon compounds are acutely susceptible to pH levels and react readily with aqueous sulfur dioxide to produce dramatic visual changes. This reactivity not only provides colorful chemistry suitable for demonstrations and student labs, but also illustrates the real-world effects of environmental contamination and the potential for use of natural plants as chemical bio-sensors.

Key Words: Laboratories and Demonstrations; general chemistry;bio-sensors

(*) Corresponding author. (E-mail: rosejeff@isu.edu)

Article in PDF format (267 KB) HTML format

Supporting Materials:

Supporting materials include a short video of sulfur dioxide bleaching red rose petals. The video includes brief instructions, chemical reactions and a time lapse of the process carried out in a petri dish. Additionally, a separate materials list outlines reagent preparations and supplies needed for teacher demonstrations and for student laboratories. (2057 KB)

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