Acids and Bases

Laboratory thirteen focuses on uses floral pigments as litmus solutions for determining whether something is an acid or a base.

Myleen works on extracting floral litmus solutions. Plants include the flowers of Hibiscus tiliaceus, Hibiscus rosa-sinensis, the orchid Spathoglottis plicata, and the leaves of coleus. Many other leaves and flowers were tested by the students.

The optimal goal was to find a single floral solution that exhibited unique color changes in reaction to an acid or a base. The floral fluid on the left, normally magenta, has turned pink in the presence of an acid and dark grayish-blue in the presence of a base.

Sally-Jean examines a print-out of X11 colors to determine the color of her floral solution. Alfonso records data.

Lynn looks down the table of unknowns to be tested, Warren at the far end.

Verne tests unknowns while making notes. Each term, even each period, tends to find different plants that work differentially well. There are differences in pigment concentrations in some flowers such as H. tiliaceus during the course of the day. This year the purple Spathoglottis orchid appeared to perform well, although it may have an anomalous reaction to mineral lime (calcium carbonate).

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