MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Universal indicator solution (from bottle at right) being added to an aqueous solution of hydroxide formed from an alkali metal. As their name indicates, alkali metals react to form alkaline solutions (of hydroxides) in water. The universal indicator solution, an acid-base indicator, has turned purple on contact with the hydroxide solution, confirming that the solution is alkaline.
Model release not required. Property release not required.