Q&A for How to Make an Indicator Using Hibiscus Petals

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  • Question
    What is the difference between acids and bases?
    Chris Hasegawa, PhD
    Retired Science Professor & Dean
    Dr. Chris Hasegawa was a Science Professor and the Dean at California State University Monterey Bay. Dr. Hasegawa specializes in teaching complex scientific concepts to students. He holds a BS in Biochemistry, a Master’s in Education, and his teaching credential from The University of California, Davis. He earned his PhD in Curriculum and Instruction from The University of Oregon. Before becoming a professor, Dr. Hasegawa conducted biochemical research in Neuropharmacology at the National Institute of Health. He also taught physical and life sciences and served as a teacher and administrator at public schools in California, Oregon, and Arizona.
    Retired Science Professor & Dean
    Expert Answer
    The basic difference between acids and bases is the difference in the amount of ions in those solutions and how those are put out.
  • Question
    How do I make an indicator using a local flower?
    Community Answer
    The same basic way. Any brightly colored part of a plant can be used as an indicator.
  • Question
    What type of natural base can I use to test for alkalinity?
    Community Answer
    Ammonia water, sold in 1/2-gallon jugs in the grocery store, is basic and will correctly test the indicator.
  • Question
    Which property of hibiscus enables it to act as a pH indicator?
    Community Answer
    Hibiscus contains anthocyanin. This is a substance that determines a plant's color, i.e. red, pink, violet, etc.
  • Question
    What is an indicator when referring to using hibiscus petals?
    Community Answer
    An indicator tells you whether the substance is an acid or base.
  • Question
    After the juice is ready, what will happen if we add lemon juice to it?
    Community Answer
    It will turn magenta (dark pink) or highlighter red, as mentioned above.
  • Question
    How long does it take to make an indicator using hibiscus flowers?
    Community Answer
    Depending on your speed, it should take less than half an hour.
  • Question
    What is the purpose of the ethanol in this indicator?
    Community Answer
    The ethanol is used for an easy and effective extraction of the red pigment from the hibiscus flower.
  • Question
    What is the purpose of the ethanol when making indicators using hibiscus petals?
    Community Answer
    Ethanol belongs to a class of organic compounds called alcohols. Ethanol is quite effective in extraction of pigments, for which it is used here.
  • Question
    Why does hibiscus flower indicator change color when added to an acid/base?
    Hannah Madden
    Community Answer
    Hibiscus flowers have anthocyanin in them, which is what gives them their color. This pigment automatically reacts with chemicals and changes different colors depending on their acidity or basicness.
  • Question
    Does the hibiscus indicator work only if it is freshly prepared? Can I preserve it?
    Hannah Madden
    Community Answer
    Chemical indicators work best if you use them right away. Preparing your hibiscus indicator a day ahead of time is probably fine, but if you wait much longer than that it won't work as well.
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