278
Experimental
IN THIS CHAPTER
Summary:The free-response portion of the AP exam will contain a question
concerning an experiment, and there may also be a few multiple-choice ques-
tions on one or more of these experiments. This chapter reviews the basic
experiments that the AP Exam Committee believes to be important. You should
look over all of the experiments in this chapter and pay particular attention to
any experiments you did not perform. In some cases you may find, after read-
ing the description, that you did a similar experiment. Not every AP class does
every experiment, but any of these experiments may appear on the AP exam.
The free-response questions on recent exams have been concerned with
the equipment, measurements, and calculations required. In some cases,
sources of error are considered. To answer the question completely, you will
need an understanding of the chemical concepts involved.
To discuss an experiment, you must be familiar with the equipment
needed. In the keywords section at the beginning of this chapter is a com-
plete list of equipment for the experiments. Make sure you are familiar with
each item. You may know an item by a different name, or you may need to
talk to your teacher to get additional information concerning an item.
In some cases, the exam question will request a list of the equipment
needed,while in other cases you will get a list from which to choose the items
you need. Certain items appear in many experiments. These include the ana-
lytical balance, beakers, support stands, pipets, test tubes, and Erlenmeyer
flasks. Burets, graduated cylinders, clamps, desiccators, drying ovens, pH
meters, volumetric flasks, and thermometers are also commonly used. If you
are not sure what equipment to choose, these serve as good guesses. Most
of the remaining equipment appears in three or fewer experiments.
You will need to know the basic measurements required for the experiment.
For example, you may need to measure the initial and final temperatures. Do
not make the mistake of saying you measure the change in temperature.CHAPTER
19
KEY IDEA