Analysing and Solving Chemistry Problems

If you're like many students studying chemistry, one of the most frustrating obstacles you face is solving chemistry problems. (That's probably why you've turned to this Supplement.) Our goal here is two-fold. First, of course, we want to help you apply chemical concepts to solve chemistry problems. Second, we want to help you develop better problem solving skills in general-skills that you can apply in other settings besides chemistry. Because of the limited space available here, we will not attempt to cover all of the kinds of chemistry problems you will encounter. Instead, we will focus on three of the most important areas that you're likely to struggle with early in the course-areas that, once mastered, will enable you to easily conquer the rest. These are: 1. Unit conversions and the factor-label method, 2. SI units and conversions, and 3. The mole concept and stoichiometric calculations. We will discuss them in the order in which they are presented in the textbook, so if you encounter something unfamiliar while working with the Supplement, it's probably because you haven't encountered it yet in class or in your reading of the text. We urge you to postpone studying a topic in this Supplement until it's been presented to you in class and until you've studied the topic in the textbook.

Becoming a Problem Solver

Becoming a good problem solver involves developing a way of thinking about problems. You have to look for ways to break the problem down into simpler parts and you have to search your knowledge base for information that you can apply to the specific problem at hand. Sometimes it helps to rephrase the problem in your own words. There are times when you might recognize that there is a critical step that will be necessary at some central point in the problem. If so, then you can look for ways to work both backwards, toward the information you have at the start of the problem, and forwards toward the answer you seek. One of the most important things to understand is that there is no single, "one way" so solve all problems. You must work on developing your abilities to think, and toward this end, we will provide you with a framework within which to sharpen these abilities.

How to Use the Supplement

Before we begin, it is imperative that you realize that this Supplement is not a replacement for your lecture class or textbook. There are no shortcuts. To earn a good grade in your course you must begin with a positive attitude, and you must attend class. You must also study the textbook, which has been carefully written to assist you in developing the skills you need to learn the subject. You should turn to this Supplement when you feel you need a further in-depth discussion of problem solving. The Supplement is divided into sections, each dealing with a particular topic. Within each section you will find a Skills Analysis, a brief review of the subject, one or more worked Problems, and a set of Additional Problems.

Contents

1. Unit Conversions and the Factor-Label Method
2. SI Units and Conversions
   SI Prefixes-Relating SI Units
   Relating Length, Area and Volume
   Relating Mass and Volume for a Single Substance
3. The Mole Concept and Stoichiometric Calculations
   The Mole Concept,
   Relating Moles of One Substance to Moles of Another
   in a Compound,
   Relating Mass and Moles,
   Relating Masses of Substances in Compounds,
   Dealing with Individual Atoms and Molecules,
   Empirical and Molecular Formulas,
   Balancing Chemical Equations,
   Limiting Reactant Calculations,
   Relating Moles of Solute and Volume of Solution,
   Relating Volumes and Concentrations
   of Reacting Solutions