Students will analyze the bond energy of the reactants and products in a chemical reaction. Students will develop a model to illustrate how the changes in total bond energy determine whether the reaction is endothermic or exothermic.
This lesson results from a collaboration between the Alabama State Department of Education and ASTA.
This episode of Crash Course Chemistry dives into the HOW of enthalpy. How we calculate it, and how we determine it experimentally--even if our determinations here at Crash Course Chemistry are somewhat shoddy.
Life is chaos and the universe tends toward disorder. But why? If you think about it, there are only a few ways for things to be arranged in an organized manner, but there are nearly infinite other ways for those same things to be arranged. Simple rules of probability dictate that it's much more likely for stuff to be in one of the many disorganized states than in one of the few organized states. This tendency is so unavoidable that it's known as the 2nd Law of Thermodynamics. Obviously, disorder is a pretty big deal in the universe and that makes it a pretty big deal in chemistry. It's such a big deal that scientists have a special name for it: entropy. In chemistry, entropy is the measure of molecular randomness, or disorder. For the next thirteen minutes, Hank hopes you will embrace the chaos as he teaches you about entropy.
In this video, Hank takes us on a quick tour of how thermodynamics is applied in chemistry using his toy trebuchet as an example. He explores the vast, somewhat confusing, concept that everything is comprised of energy--even mass.
In this episode, you'll learn what the state function is, and how it varies from a path-dependent function; why enthalpy change is different from heat; that bonds are energy and to form and break them they release and absorb heat to and from their environment. You'll get the quickest introduction to calorimetry ever (more on that in upcoming episodes) and learn the power of Hess's Law and how to use Germain Hess's concept of the standard enthalpy of formation to calculate exactly how much heat is produced by any chemical reaction.