It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
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.
Why don't oil and water mix?
Salt dissolves in water; oil does not. But why? You can think of that glass of water as a big, bumpin' dance party where the water molecules are always switching dance partners -- and they'd much rather dance with a salt ion. John Pollard explains how two chemistry principles, energetics and entropy, rule the dance floor.
The chemistry of cold packs
If you stick water in the freezer, it will take a few hours to freeze into ice. How is it, then, that cold packs go from room temperature to near freezing in mere seconds? John Pollard details the chemistry of the cold pack, shedding light on the concepts of energetics and entropy along the way.