Chemistry from the flower garden into the kitchen
What floral pigments make the best detectors of acids and bases? What substances are acids, bases, or neutral?
This laboratory explores whether flower petal pigment solutions are good indicators of acids and bases. The flower petal pigment solutions are produced by boiling flower petals in water. If a flower petal solution is found that is a good detector of both acids and bases, then that solution will be used to determine whether unknown substances are an acid, a base, or neutral. Flower pigment solutions are also called floral pigments in this laboratory.
In the English language acids are said to be sour or tart. Bases are often said to be bitter.
Demonstrate litmus paper and its reaction to the known acid and base. Note that litmus paper is not always available. In lieu of litmus paper paper, one can produce litmus solutions.
There are three phases to this laboratory.
Collect the flowers and leaves, boil them.
Test each floral solution for color changes, including changing to clear or clear changing to a color.
Make a table [d][t] of your results for the various flowers noting the color change, if any, caused by the known acid or the known base. The table should include:
Tables are intentionally omitted. At this point in the term students are being marked on their ability to design meaningful tables without direct guidance.
Use flower petal solutions that change color in a consistent way for acids or bases. If you find one that changes color for both acids and bases, use that one. If you find that one changes colors for acids and another changes color for bases, use both of those two floral pigment solutions. These floral solutions can also be called "litmus" solutions.
Use the solution to analyze [a] whether the following household substances are acids or bases (different compounds might be made available on lab day):
Make a table [ta] of your results for the household substances noting the color change and whether the substance is an acid, a base, or neutral.
[c] Conclusion. Discuss what flowers showed the most distinct color change for the known acid. Discuss what flowers showed the most distinct color change for the known base. Discuss any difficulties you encountered.