High-speed footage of a large chunk of sodium metal reacting violently in water. Initially shown in slow motion, the metals fall into the water, and turns the surrounding water pink. This is due to the acid-base indicator phenolphthalein in the water, which turns pink in contact with the sodium hydroxide formed in the reaction. © Rhys Lewis & Minh Tan Pham, AHS/DECD/ SPL / Science Source
