Floral pigments as litmus solutions

Laboratory thirteen in physical science had the students collect flowers from around campus, produce floral solutions by boiling in water, and then test to see which floral solutions changed color for both a known acid and a known base. Teaching in the tropics makes this laboratory possible in both November and April, or even in July.

Pertin holds up a floral pigment solution that was purple and turned green and then yellow in the presence of a base.
Leslie shows off her floral solution.

McHelita compares the original floral pigment solution to one with an acid added (the pink test tube) and one with a base added (greenish on the far right).

Randy obtains a color change to pink that is indicative of the added solution being an acid. This term the students examined ammonia, bleach, sodium hydroxide (Drano), aspirin, anti-acid tablets (Rolaids), salt, vinegar, and Pine Sol. Pine Sol turned out to be a base.

The laboratory continues to be enjoyable for both the students and myself and a good demonstration of low input chemistry. All of the chemicals are locally obtained, only the glassware is ordered from off-island.

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