You and a friend are hiking the Appalachian Trail when a storm comes through. You stop to eat, but find that all available firewood is too wet to start a fire. From your Chem 106 class, you remember that heat is given off by some chemical reactions; if you could mix two solutions together to produce an exothermic reaction, you might be able to cook the food you brought along for the hike. Luckily, being the dedicated chemist that you are, you never go anywhere without taking along a couple chemical solutions called X and Y just for times like this. The Virtual Lab contains solutions of compounds X and Y of various concentrations.

You probably remember the mole from high school chemistry, but do you remember why it is useful to chemists? The goal of the following video is to give the "big picture" of the mole and its applications; information on how to use the mole in calculations can be found in another tutorial. 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 term refers to the mass, not the weight, of substance, and (ii) that the quantity refers to a mole of a substance, not a single molecule. "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.

During the first kinetics lecture, we traced the efforts of atmospheric chemists to explain the depletion of ozone in the upper atmosphere. (The powerpoint slides have been posted on Blackboard for your review.) U2 spy planes gathered much of the initial data that linked ClO in the stratosphere to the ozone depletion. The data collected during these flights showed the concentrations of various chemical species in the stratosphere, but did not measure how fast the processes were occurring. To determine the kinetics (rates) of ozone depletion reactions, chemists perform controlled laboratory studies. In this homework, we will interpret data obtained from such laboratory experiments to study the ozone depletion reaction.