View full lesson: http://ed.ted.com/lessons/what-triggers-a-chemical-reaction-kareem-jarrah

Chemicals are in everything we see, and the reactions between them can look like anything from rust on a spoon to an explosion on your stovetop. But why do these reactions happen in the first place? Kareem Jarrah answers this question by examining the two underlying forces that drive both endothermic and exothermic chemical reactions: enthalpy and entropy.

Lesson by Kareem Jarrah, animation by Flaming Medusa Studios Inc.