Laboratory Syllabus

 
The Chemistry 121 laboratory course is designed to demonstrate scientific principles studied in lecture, to provide practice in fundamental chemical laboratory techniques, and to simultaneously give an introduction to the methods of quantitative chemical analysis.

Your laboratory grade contributes 25% to your final grade in Chem 121; 80% of the lab grade is determined by the lab reports you will hand in during the semester; and 20% by instructor evaluation. Each lab report is worth 25 points.

A formal lab report is required for each lab unless otherwise instructed.  Lab reports will follow this format Note: this is slightly different from the lab manual format.

1. Abstract

An abstract of the experiment is to appear on the first page of each lab report. An abstract of an experiment is a short paragraph (3-4 sentences) stating what was done (not what was set out to be done) in a given experiment. It is not a description of the experimental procedure. No data is given in the abstract. Only the final numerical results should be included, and, if applicable, a statement of how the results deviated from expected values. The correct form and wording of an abstract, which is found at the beginning of every research article published in chemistry, may be seen in any chemistry journal in the library.

The following is a reasonable abstract for an experiment in which a pipet is calibrated:
 

 A 25 ml transfer pipet was calibrated by weighing, on an analytical balance, various samples of water delivered by the pipet. The percent error of the manufacturer's etch mark was found to be 0.15%.

2.  Procedure  

Each lab report will include a brief (no more than one paragraph) description of how you collected the data.  

3. Data

Data should be presented in the form of a table whenever possible; this is the clearest, most concise method of displaying many individual pieces of data.

4. Calculations

In general you will take data, perform some mathematical operations on it, and thereby compute scientific results of interest. A subsection entitled "Calculations" is always required to show how you converted the experimental data to the desired results. If a calculation is performed more than once (as is often the case), one sample calculation is sufficient, providing you explicitly state that your other results were computed in an analogous manner.

It is important that the source and derivation of all numbers in a calculation be obvious. The best procedure is to write the equation you are using, and then on the second line substitute into the equation all known parameters. On the succeeding third and fourth lines solve the equation for the unknown.

Significant Figures must be observed in the reporting of all results. It is permissible to carry out calculations without regard to significant figures, and then to round off the result to the proper number of significant figures. Failure to correctly round off will result in loss of credit.

5. Results

Results should be put in as organized a manner as possible. Tables are preferred for numbers.

COPYING THE LAB MANUAL IS NOT ACCEPTABLE! Be creative. Results can sometimes be presented at the end of the data table, with clear subject headings indicating "Data" and then "Results."

6. Discussion and Error Analysis

The end of each lab report should be the examination of the laboratory. It does not have to be more than two short paragraphs. The first paragraph should discuss what principles were examined and what you learned from the experiment. The second should be the error analysis, in which you are to discuss probable sources of error (not just possible ones like global warming) in the experiment. For each possible source of error given, you must include the approximate magnitude and the direction that it would shift the final result. With these considerations, it can be determined which source of error may have actually contributed to making the experimental value incorrect.

Lab Notebooks

I require all students to keep a lab notebook. This should be a bound book (no spiral binding) such as a composition book (60 pages or so) which you bring to every lab session. A large part of my evaluation of your lab performance will be based on spot checks of this book.

Notebooks are an immense help in preparing for lab. A typical notebook entry will have the experiment number and title at the top of the page as well as the date. A brief outline of procedure will help you organize your time. This does not mean that you should copy verbatim the procedure! The next part should be a data table ready to fill in. Leave space for pre-lab lecture notes and possible sources of error.

Pages should be numbered sequentially and the first two pages left for a table of contents.

General Considerations

1. Lab reports are due one day after the last scheduled lab session for that experiment. A lateness penalty of 10% per lab session will be assessed for late lab reports. Reports are due at the beginning of the lecture. No lab reports will be accepted after the last lab session.

2. There are no make up labs. If you are out sick, it will not count against you; your lab grade will be calculated based on the labs you were present for. Department policy is that any student missing more than two lab periods will get a failing grade for the entire course, including the lecture.

3. All lab reports will be typed. I may penalize up to 20% of full credit for lack of neatness, poor legibility, or grammatical errors.

4. It is important that students come to lab fully prepared and ready to work. Do not enter the lab and then stand at your bench reading the manual for the first time. The lab session ends promptly at the specified time: the instructor will announce clean-up 10 minutes prior to that. I may penalize students for lack of preparation, for poor (including unsafe) lab technique, and for being late out of lab.

5. The lab must be left clean when the class leaves. It is the responsibility of each student to make sure when he leaves the lab that any bench space, balance, or other piece of equipment used that day by the student is clean.