BEAUTIFULCHEMISTRY.NET / SCIENCE PHOTO LIBRARY BEAUTIFULCHEMISTRY.NET / SCIENCE PHOTO LIBRARY
Close-up timelapse footage of the growth of a chemical garden . This is a solution of sodium silicate (also called glasswater, or liquid glass) to which a metal salt has been added. In this case, the salt is cobalt (II) chloride. The salt partially dissolves in the water and the ions react to form a thin layer of insoluble cobalt silicate. This layer is semi-permeable, and the more concentrated salt solution inside the tube pushes outwards due to osmosis. This bursts the tube, releasing more salt solution and forming a new tube, and the process continues. As the pressure is greater further down the water column, the tubes grow upwards. The colour of the tubes depends on the transition metal used. In this case, the colour change from pink to blue is due to the change in hydration of the cobalt ions. This clip is speeded up 10 times.
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