BEAUTIFULCHEMISTRY.NET / SCIENCE PHOTO LIBRARY BEAUTIFULCHEMISTRY.NET / SCIENCE PHOTO LIBRARY
Close-up timelapse footage of the petals of a Torenia fournieri flower in a solution of alkaline sodium hydroxide, showing the change in colour. The pigment chemicals in this flower act as a natural acid-base indicator, here seen to change colour to yellow in the presence of an alkali. This clip has been sped up 40 times. See clip K004 5182 for the flower in an acid.
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