MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Universal indicator rainbow experiment. Test tube showing a range of colours indicating a range of pH values. This colour banding is obtained using universal indicator, with a sodium carbonate crystal in the bottom of a test tube of water and acid at the top. This banding develops as the alkali (dark purple) and acid (red) meet. The neutral region is indicated by the narrow green band. Yellow is slightly acidic. This experiment can also be carried out using sodium hydroxide.
Model release not required. Property release not required.