The Free-Response Questions

In the table that follows, keep in mind that only the general topics are listed. There are some questions in the Ifee-response questions that require you to integrate topic areas (e.g., free energy and equilibrium). In such instances, the primary topic of the question is listed. Also, there is no distinction of whether the question was a Section I (calculator) or a Section II (noncalculator) question. Finally, because the question with the eight reactions (from which you select five) appears every year, these have been omitted in the interest of space. 

Remember, in this section there are three questions, one required and two from which you select one. The first problem deals with some aspect of equilibrium and will consist of several parts, usually from five to seven. Each part is worth 1 or 2 points, for a total of 9 points. Average scores on this problem tend to be somewhere around 4. The two optional problems also contain multiple parts, with each worth 9 points. Scores on this question range from 4 to 5. 

The second point to remember is that the grader does not know you. While this may be a rather obvious statement, there is a reason for mentioning it. Your teacher, despite his or her best attempts to be objective, may give you a little leeway on grading because he or she knows you and knows what you probably meant to say in your essays. The graders for the AP exam don t 

Empirical formula, molar mass (freezing point depression), molar mass (vapor density) A, AG 

Essays graph interpretation (activation energy, rate, rate law) 

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You will receive a test booklet for the free-response section of the test. You will have 95 minutes to answer six questions. These questions may cover any of the material in the AP Chemistry course. Section II consists of two parts. In the first part, you may use a calculator. You will have 55 minutes to answer three questions, the first of which will deal with equilibrium. In the second part, you may not use a calculator. You will have 40 minutes to answer three questions, the first of which will be a reaction question. One of the free-response questions will address laboratory work. The first part will account for 60% of your... 

Your score on the free-response questions (FRQs) amounts to one-half of your grade and, as long-time readers of essays, we assure you that there is no other way to score highly than to know your stuff. While you can guess on a multiple-choice question and have a 1/5 chance of getting the correct answer, there is no room for guessing in this section. There are, however, some tips that you can use to enhance your FRQ scores. 

Read the question carefully. The free-response questions tend to be multipart questions. If you do not fully understand one part of the question, you should go on to the next part. The parts tend to be stand-alone. If you make a mistake in one part, you will not be penalized for the same mistake a second time. 

Make sure you spend some time on each section. Grading of the free-response questions normally involves a maximum of one to three points for each part. You will receive only a set maximum number of points. Make sure you make an attempt to answer each part. You cannot compensate for leaving one part blank by doubling the length of the answer to another part. 

Questions concerning experiments may be incorporated into both the multiple-choice and free-response questions. Beginning with the 2007AP Chemistry Exam, experimental questions may be incorporated into any of the free-response questions. This means that you will need to have a better understanding of the experiments in order to discuss not only the experiment itself but also the underlying chemical concepts. 

The first parts of the free-response questions are usually the easiest parts. Spend just enough time to get these points before moving on to the more difficult sections. 

Some substances will dissolve in a particular solvent and others will not. There is a general rule in chemistry that states that like dissolves like. This general statement may serve as an answer in the multiple-choice questions, but does not serve as an explanation in the free-response questions. This simply means that polar substances (salts, alcohols, etc.) will dissolve in polar solvents such as water, and nonpolar solutes, such as iodine, will dissolve in nonpolar solvents such as carbon tetrachloride. The solubility of a particular solute is normally expressed in terms of grams solute per 100 ml. of solvent (g/mL) at a specified temperature. The temperature must be specified because the solubility of a particular substance will vary with the temperature Normally, the solubility of solids dissolving in liquids increases with increasing temperature, while the reverse is true for gases dissolving in liquids. 

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. 

Now it s time to start. Read the Introduction The Five-Step Program Chapter 1, What You Need to Know About the AP Chemistry Exam and Chapter 2, How to Plan Your Time. Then, take the Diagnostic Exam in Chapter 3. Your score will show how well you understand the material right now and point out weak areas that may need a little extra attention. Use the review exams at the end of the chapters to check your comprehension. Also pay attention to the free-response questions. That is where you can really shine, and they are worth almost as much as the multiple-choice part. Use the Rapid Reviews to brush up on the important points in the chapters. Keep this book handy—it is going to be your friend for the next few weeks or months. 

Learn how to plan and write answers to the free-response questions. 

For the free-response questions, you will be given a separate packet. The first part of the packet consists of your answer booklet. All answers are to be written here. You will also be given a green packet that contains the questions and a great deal of reference material—a periodic table, a table of standard reduction potentials, and several pages of formulas and constants (shown in the following Tables 1.1 through 1.7). 

The second variation is to determine either the pH or the hydrogen ion concentration of a solution when given the hydroxide ion concentration, [OH-], for the solution. To solve these problems you need to utilize the equilibrium constant expression for the self-ionization of water (Kw). This expression will allow you to convert from the hydroxide ion concentration, [OH-], to the hydrogen ion concentration, [H+], The [H+] can then be used to calculate pH if necessary. One of the free-response questions on the 1999 test required this calculation. 

Show all of your work on the free-response questions. If you only show your answer, and it happens to be incorrect, the grader has no choice but to give you no credit for the entire question. Writing down all of your steps makes sense. 

Be neat on the free-response questions. Let the grader focus on content, rather than the form. The answers are not lengthy, so do your best to be neat and organized. 

Students who completed the static version had negative comments only or did not answer the free response questions about the module. Some of their comments include ... 

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