Problem Sets

Two of the most important aids to your gaining an understanding of the material in Chemistry 102 are regular class attendance and the conscientious completion and review of the Problem Sets. These problem sets will be collected, graded, and comprise about 15% of your final grade. The two lowest-grade problem sets will be discarded, and no extensions will be given. Don't "waste" your throw-away grades! You may need it for a family emergency, athletic competition, or heavy workload from other classes. You may work on the problems with other Chemistry 102 students (which is often very helpful), and you should feel free to consult with me if you are having trouble with particular problems. It is also helpful to look at the way sample problems are worked out in your lecture notes, the text, or on part A of problem sets. If, upon completion of any given problem set, you do not feel confident in your ability to solve certain problems, look for similar ones in the text and attempt them. The part B problems given on the assignment sheets represent a minimum number that you should complete - these are the ones to submit for grading.

Each problem set will probably require about eight hours to complete so you should not attempt to do any problem set in one night (or put it off until the day before it is due). You should try to work the problems in a way that corresponds to the order in which the material is covered in class. In this way you will spread the problem set over several days and also reinforce the lecture material as it is presented.

Problems in part A of the problem set are for practice. The answers to the part A problems will be placed on reserve in Sawyer and in the chemistry library on the day (or the day after) the problem set is handed out in class. Problems in part B are to be submitted. Late problem sets will not be accepted. Your method must be clearly indicated to receive full credit. A complete answer to a numerical problem shows three parts:

1. the Equation used.

2. Substitution of numerical values with units into the equation.

3. the correct Answer, with the correct number of significant figures.

You will make the graders happy if you place a box around your answer. It is also helpful to restate the question when providing an answer. For example, write "iron (III) chloride = FeCl3", rather than just "FeCl3". Be neat. No effort will be made to decipher illegible, messy hieroglyphics. Be certain that separate sheets have your name on them and that they are stapled together. There is a stapler on the window ledge in the Chemistry Library. The graded problem sets will be returned to you and, at that time, the solutions to the part B problems will be posted in the Chem 102 home page.

Significant figures: For homework and examinations in this course, you are expected to use four significant figures in atomic masses. For example, use the following grams/mole: 1.008, H; 14.01, N; 55.85, Fe; and 118.7, Sn. Use the rules for retention of significant figures in addition, subtraction, multiplication, and division to produce an answer with as many significant figures as is appropriate for that problem. In general, carry extra significant figures in intermediate calculations, and round off only on the very last step. An incorrect number of significant figures is the most common way to lose points in Chem 102

It is particularly important to use the correct units when reporting an answer. Only up to half credit will be given for answers with missing, or incorrect units. Note that reporting an answer in grams rather than kilograms is acceptable, but dimensionless rather than grams is unacceptable.

All problems from

"Chemistry"

6th Ed.

by

R. Chang

Problem Set # 1

Due 9:00a.m., Friday-Feb-09-01