A Laboratory Manual

Experiments compiled by C. M. Lang

for Chemistry 100 – Fall 2005

University of Wisconsin – Stevens Point

A Laboratory Manual

Compiled by C. M. Lang

Department of Chemistry University of Wisconsin – Stevens Point

For use in Chemistry 100 (Fall 2005)

in conjunction with Chemistry in Context – 5th ed.

published by The American Chemical Society

To my students …

This course has recently been re-titled “Chemistry for the Citizen” in conjunction with a revision in the course’s mission … Environment Literacy. These experiments were first drafted for the Fall Semester 2004 and are currently being revised for use during Fall Semester 2005. The experiments have been designed and chosen to reflect and amplify the contents of the textbook entitled Chemistry in Context – 5th Edition. My objective in compiling these experiments was not to train future chemists, but rather to show what chemists do and how they do it. I would also like for you to appreciate the fact that there is no great mystery to doing chemistry in the laboratory. A great deal of chemical information about the world around you can be obtained with simple equipment, modest procedures, and can be conducted safely! As citizens, you need to be aware of the contributions chemists, chemical scientists and the engineers have made to the knowledge base of humankind … an awareness based on acquiring data, understanding the ramifica-tions of that data and making sound decisions based on that data. Our planet is beset by many problems. Many, many solutions are suggested and ultimately decisions made based on “scientific evidence.” In some small way, it is hoped that “Chemistry for the Citizen” will give you some critical tools whereby you can analyze “scientific evidence” for its reasonableness and credibility. Another goal is to give you an opportunity to explore how chemists solve problems. After all, chemistry is an experimental science, and many chemists and scientists spend a large part of their time in a laboratory. Like practicing chemical professionals, you will use the laboratory to try out ideas, investigate the properties of materials and compounds, synthesize compounds, analyze materials, and, in general, solve problems. Hopefully, the chosen experiments will show you how it is done. You will find that for most of these experiments, rather simple equipment is used and that you can easily learn the necessary techniques. In general, you will be working with a partner, and in some cases, the class will work collaboratively to collect data and answer a scientific question. For nearly every experiment, you will find one or more data sheets at the end. Unless I direct otherwise, you should record all observations and data on these sheets. It is important to make these recordings while you are doing the experiment – not at some later time when you may have forgotten the details. Each experiment also includes a set of questions to be answered after completing the experiment. These questions are designed to help you consolidate what you have learned and to demonstrate your understanding. Although you may never again work in a chemistry laboratory, it is my hope that after this laboratory course, you will understand why chemical professionals find laboratory work so interesting and compelling.

C. Marvin Lang August 2005

Some Notes About Laboratory Safety

Good laboratory practice requires that you take some simple safety precautions whenever you work in a chemistry laboratory. The popular notion that a chemistry lab is a dangerous place, filled with unknown disasters waiting to occur, is simply untrue for most situations and is certainly incorrect for the activities in this laboratory text. Nevertheless, all chemistry laboratories have some potential hazards associated with chemical splashes, careless handling of flammable substances and glassware breakage. With this in mind, what follows are some basic rules that you must adhere to when working in a chemistry laboratory.

1. Wear approved eye protection at all times. This is the most essential rule and

will be rigidly enforced. Chemical splashes are most serious with regard to your eyes. Even dilute solutions of many chemicals can cause serious eye damage upon contact. Fortunately, your eyes are very easy to protect by wearing approved safety glasses or goggles. Even when you are not working directly with chemicals, someone near you may have an accident and something may splash or fly in your direction.

2. Exercise special care whenever you are using flammable chemicals. There

must be no open flames anywhere in the vicinity of your work. Even a hot object can sometimes cause flammable vapors to ignite. This means that you must know which liquids are flammable.

3. Never eat, drink, or smoke in the laboratory. Some chemicals are very toxic.

4. Never perform unauthorized experiments. Some simple chemicals can form

explosive or toxic products when mixed in unintended or inappropriate ways.

5. Never work in a laboratory without proper supervision. One of your best safety precautions is to have a knowledgeable person present who can spot potential hazards and handle an emergency should it arrive.

6. Handle glassware carefully. Glass can break and can cause nasty cuts.

7. Learn the location of fire extinguishers, a fire blanket, first-aid kit,

eyewashes, and safety showers in your lab. Be sure you know how and when they are to be used.

For many of the experiments in this text, you will find specific safety notes highlighted in boxes. These must, of course, be followed. But, above all, you should develop a habit of working safely and being safe! Finally, you are expected to attend one laboratory session each week … normally the one for which you are enrolled. Contact me if other arrangements must be made for a particular week. Please note that all cellular phones, electronic pagers and other personal communication devices must be turned off during laboratory sessions.

Essay: The Wonder of Chemistry Experiments

The quote below, taken from F. H. Getman’s article on the life of Ira Remsen*, has often been cited by chemists in lectures and texts – perhaps because it reminds them of some similar incident that happened to them during their adolescent years and influenced their decision to become chemists. I quote it because it conveys, in a charming way, the message that you can’t really know some aspects of chemistry unless you experience them for yourself. While we certainly hope you will come away from laboratory sessions with your clothes and skin intact, I would also like you to come away with some of the wonder and interest in chemistry that was kindled in Ira Remsen by his first laboratory experience. Remsen went on to become one of the foremost American chemists of the nineteenth century.

While reading a textbook of chemistry, I came across the statement, “nitric acid acts on copper.” I was getting tired of reading such absurd stuff and I was determined to see what this meant. Copper was more or less familiar to me, for copper cents were then in use. I had seen a bottle marked nitric acid on a table in the doctor’s office where I was then “doing time.” I did not know its peculiarities, but the spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words “act upon” meant. The statement “nitric acid acts upon copper” would be something more than mere words. All was still. In the interest of knowledge I was even willing to sacrifice one of few copper coins then in my possession. I put one of them on the table, opened the bottle marked nitric acid, poured some of the liquid on the copper and prepared to make an observation. But what was this wonderful thing which I beheld? The cent was already changed and it was no small change either. A green-blue liquid foamed and fumed over the cent and over the table. The air in the neighborhood of the performance became colored dark red. A great colored cloud arose. This was disagreeable and suffocating. How should I stop this? I tried to get rid of the objectionable mess by picking it up and throwing it out the window. I learned another fact. Nitric acid not only acts on copper, but it acts upon fingers. The pain led to another unpremeditated experiment. I drew my fingers across my trousers and another fact was discovered. Nitric acid acts upon trousers. Taking everything into consideration, that was the most impressive experiment and relatively probably the most costly experiment I have ever performed… It was a revelation to me. It resulted in a desire on my part to learn more about this remarkable kind of action. Plainly, the only way to learn about it was to see its results, to experiment, to work in a laboratory.

* From The Life of Ira Remsen, published by the Journal of Chemical Education, of the Division of Chemical Education Inc., of the American Chemical Society.

A Laboratory Manual Compiled by C. M. Lang

Department of Chemistry University of Wisconsin – Stevens Point

List of Experiments

Experiment #1 – Properties of Selected Gases and Data Handling

Experiment #2 – Spectroscopy: Colored Solutions and U.V.

Experiment #3 – Chromatography: Gas and Paper

Experiment #4 – Microscale Gas Chemistry

Experiment #5 – Chemical Reactions: Making Table Salt

Experiment #6 – Chemical Bonds, Molecular Models and Shapes

Experiment #7 – Energy Content of Selected Fuels

Experiment #8 – Investigating Water Conductivity

Experiment #9 – ACIDS: Reactions and Analysis

Experiment #10 – pH Measurements of Common Substances

Experiment #11 – Solubilities: An Investigation

Experiment #12 – Radioactivity and the Half Life of 40K

Experiment #13 – Electrochemical Cells

Experiment #14 – Polymer Chemistry

Selected Laboratory Equipment