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 hydrochloric acid, showing the change in colour. The pigment chemicals in this flower act as a natural acid-base indicator, here seen to change colour to pink in acid. This clip has been sped up 40 times. See clip K004 5183 for the flower in an alkali.
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