Cooking is related to chemistry because the preparation of many types of foods involves chemical reactions. When cooks understand how chemical processes work during cooking, they are able to make adjustments and produce better foods.
When cookies bake, a number of chemical reactions occur. For example, when the cookies reach 212 degrees Fahrenheit, the water in them turns to vapor. This escapes through the dough, puffing up the cookies. Baking soda and baking powder break down and form carbon dioxide, which makes cookies rise even more. Baking powder, in particular, produces carbon dioxide during both mixing and baking, so adjusting the amount of this leavening agent allows the cook to modify a cookie's density.
When cooking meat, it helps to understand the composition of the raw product. Typical meat is about 75 percent water, 20 percent protein and 5 percent fat. During cooking, much of the water escapes from the meat, and that is why it shrinks. Overcooking removes too much water.
Popcorn kernels are about 13.5 percent water, which boils and turns to water vapor when heated. Since the vapor cannot easily escape the sealed hulls of the kernel, pressure builds. At about 356 degrees Fahrenheit, the kernel explodes. If the water content is not correct, or if the hull is damaged, the kernel will not pop properly.