1. Natural pH indicators

    Litmus, methyl orange, and phenolphthalein are well-known and broadly used acid-base indicators. But did you know that some plants can also be used as indicators?

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    Natural pH indicators

    In laboratory work in a school chemistry course you often work with  substances that can change their color depending on the pH of the solution. We call these substances "acid-base indicators"; they include litmus, methyl orange, and phenolphthalein. In nature, however, we can find many more substances that change their color depending on acidity. Litmus, for example, was one of the first acid-based indicators and is derived from some species of lichen. Florists and landscapers have also noticed that the petals of lilac, hydrangea, violet, and other plants may change their color according to the acidity of the soil in which they grow.

    In this project, we will try to identify plants that can indicate pH changes with their colour/color. Working together, we can create a catalogue of these indicator plants. We also will try to determine which plant parts contain the actual substances changing with pH.

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