The Mole

You probably remember the mole from high school chemistry, but do you remember why it is a useful concept and what it allows chemists to do? The following video gives an overview of the mole and why it is useful. The goal here is to give the "big picture" of why chemists find the mole so useful. Later in the course, you will learn how to do calculations involving the mole.

Throughout this course, we will use the term "molecular weight" to refer to the mass of a mole of a substance (for instance, the molecular weight of oxygen (O₂) is 32 g/mol). Recent textbooks refer to this as "molar mass" to emphasize (i) that this is the mass of substance, not the weight and (ii) that the quantity refers to a mole of a substance. "Molecular weight" may be less precise, but it remains the term that most practicing chemists use in the laboratory. For this reason, we continue to use "molecular weight" in this course.

Text version of this movie.

Below you will find some practice questions to get you used to the concepts and calculations concerning the Mole.