Los Angeles City College Laboratory Report and Notebook Guidelines for Chemistry 101

Transcription

1 Los Angeles City College Laboratory Report and Notebook Guidelines for Chemistry 101 The following guidelines are provided to acquaint students with the expectations for maintaining a laboratory notebook as well as submitting the final laboratory report. Most laboratory activities will include preparation of a pre-lab, gathering of experimental observations and data acquisition, and submission of a formal, typed (double-spaced) report after completion of each lab. Pre-lab The laboratory notebook is first and foremost a record of one s work in the lab. If that seems obvious, consider the fact that many students INSIST on recording experimental observations and data on their hands, scrap paper, etc. A good scientist learns to work in a notebook just as surely as he/she learns to work in the lab. While an expert at lab note taking may produce a notebook that is a work of art, the ultimate aesthetic appeal of a notebook is far less important than its logical sequence and clarity as a record of investigation. Wanting it to look neat is therefore not an acceptable excuse for not entering all data and observations directly in the notebook. Please continue to develop the habit of recording ALL your observations. This cannot be emphasized enough! The purpose of the pre-lab is to allow the student to become familiarized with the basic principles of the experiment along with the tasks that he/she will be expected to execute in order to gather the appropriate data. The pre-lab will ALWAYS be checked for completion (and graded) before the student enters the laboratory. The pre-lab should contain the following: 1. at the top of the first page of an experiment: the complete experiment title the date your name lab partner (if appropriate) 2. at the top of EACH succeeding page: your name the experiment title 3. the body of the pre-lab should contain: a. Purpose Using complete sentences, briefly state the purpose or goal of the experiment. WHY ARE YOU DOING IT? WHAT ARE YOU TRYING TO FIGURE OUT? Make sure to use the active voice in this section and throughout your report. It is usually more precise and less wordy than the passive voice.

2 b. Materials and Equipment This list should contain a compilation of all the necessary chemicals and equipment necessary to carry out the experiment. c. Safety Information Before beginning any experiment, it is important to note potential hazards, safety precautions, and any pertinent physical data. Please consult the following sources for information on any chemicals used in the experiment, both reactants as well as expected products. Great resources include online Material Safety Data Sheets (see Links under my homepage), Lange s Handbook of Chemistry (available in the library), CRC Handbook of Chemistry and Physics (available in the library and in the lab room), and The Merck Index (available in the library). Students should also use these works when writing conclusions/discussions, trying to make sense out of results, and/or calculating any physical constants. If at first you don t find what you want, try again! Even the indices in CRC and Lange s can be frustrating. Finally, ALWAYS cite your source for information obtained from any of these (or other) reference works, including your textbook. Failure to properly cite is plagiarism and will result in ZERO CREDIT for the lab report and potential disciplinary action. d. Method and Data This section should explain how you intend to accomplish your task in the laboratory. Give balanced chemical equations as needed along with a logical sequence of data processing. Data should be recorded in neatly prepared and NUMBERED tables (use a ruler). Numbering of the tables will facilitate discussion of results at the conclusion of the experiment. Because experiments can extend over several days, it is important to get in the habit of dating entries in a table or on a page. e. Observations In general, record any pertinent observations. Nonnumerical information may be written in simple comment form. At the conclusion of an experiment, return all carbon pages to the instructor for grading. A photocopy of the original data recorded in your notebook along with the pre-lab MUST accompany your final formal report as an appendix. As a final note, consider the following three points: 1. use black ball-point ink when writing 2. do NOT decorate errors; a single line through an entry will suffice you may decide later it was correct after all! 3. be sure to record PRIMITIVE data for example, initial and final buret readings, not the difference done in your head

3 Format for Laboratory Reports The official laboratory report will consist of the various sections outlined below. This report must be typed (double-spaced) on 8½ x 11 paper and will be due after completion of each lab. The organization will be similar to the format established by the NSF (National Science Foundation) for manuscript and proposal submissions. Points will be deducted if a student does not adhere to this format. A sample report will be handed out in class as an example. PLEASE NOTE THAT WHILE YOU ARE ENCOURAGED TO DISCUSS DATA ANALYSIS AND THEORETICAL CONCEPTS WITH YOUR CLASSMATES, THE OFFICIAL REPORT IS TO BE YOUR OWN WORK. 1. Cover Page (TOP) Complete Title of the experiment (CENTER) Student Name (denoted with an asterisk*) and lab partner(s), if appropriate Los Angeles City College Chemistry 101 Los Angeles, California (BOTTOM) Abstract The abstract is similar to the purpose (in the pre-lab), where you should use complete sentences to briefly state the purpose or goal of the experiment. However, unlike the purpose, you should also write a statement that includes the important results (including error analysis if applicable) and any conclusions of the experiment. Once again, make sure to use the active voice in this section and throughout your report. This section should not be longer than one-half page. 2. Introduction Using complete sentences, state the fundamental physical and chemical principles involved in this experiment. Just as a good essay requires a unifying theme and logical development, this part of your report should indicate that you have some knowledge of the important principles underlying the work to be done. Properly labeled diagrams and schematics may be included in this section if helpful. In addition, you may include outside supplementary references, although it is IMPERATIVE that you cite all these sources. 3. Experimental Section This section is the procedure plan of the report, where you outline the steps followed to obtain the necessary data. Any observations made during the experiment should also be included in this section. 4. Data Present the raw data, along with appropriate units, in tabular form. The lab report forms included in the lab manual can serve as guides for organizing this particular section. 5. Results This section should include sample calculations (with units) for each step of the data reduction (if the same calculations are performed, only type out a

4 sample calculation ONCE), and make clear how results are obtained from the raw data. Error and statistical analysis of your data must be included when appropriate. Once again, the lab report forms included in the lab manual can serve as guides for the necessary calculations. Graphs may also be included in this section (appropriately sized). If so, you MUST copy and paste any graphs from EXCEL. Label all axes and give each graph a title. When graphing experimental data, please adhere to the following criteria: A. All graphs should have a descriptive title (i.e. Graph is not a title). B. Both the vertical and horizontal axes should have labels and units clearly marked. Use a ruler to draw the axes, although use of EXCEL is preferred. C. The scales chosen should reflect the precision of the measurements. For example, if temperature is known to be C, you should be able to plot the value this closely. D. The controlled or independent variable is conventionally placed on the horizontal axis. The dependent variable is graphed on the vertical axis. E. There should be an obvious small point on the graph for each experimental value. It is not necessary to include the coordinates of each point since they will be in the raw data table. F. A smooth (or best-fit if using EXCEL) line should be drawn that lies as close as possible to most of the points. Do NOT draw a line connecting one point to the next one as in a dot-to-dot drawing. 6. Discussion and Conclusion In this section, discuss your results. List any FINAL numerical results including units, statistical information, and unknown designations when appropriate. Summarize observations that appear to bear upon the validity of a particular result or the analysis as a whole. Any discussion of your calculated results is appropriate, especially if you notice that results are unexpectedly uncharacteristic or when comparing to literature values. One question you should ask yourself is: What could I have done in this experiment to obtain better results? Blaming equipment and instrumentation is NOT a legitimate recourse. Instead, you must go back through the experimental procedure and decide where an error could have been made that would result in the high/low or outrageous value. Then, you must judge the likelihood of having made such an error and explain its impact on your results. Some experiments by their nature cannot yield accurate data. This is also a possible avenue for discussion, but it must be backed up with theory. Finally, some experiments may contain a list of post-lab questions to answer. These should also be answered and included in this section of the laboratory report.

5 7. References List all references in preparing your report (at least ONE is required) by alphabetical order. This may include (but is not limited to) online Material Safety Data Sheets, Lange s Handbook of Chemistry, CRC Handbook of Chemistry and Physics, The Merck Index, and/or your textbook. Remember that the reference MUST be cited (i.e. numbered) in the portion of your report where it is used. References should be cited in a standard form: Author s name (last name first). Journal or book title. Year of publication, volume number, pages cited. e.g. Schrauzer, G.N. and Windgassen, R.J. J. Am. Chem. Soc. 1966, 99, Appendix This will be a copy of your pre-lab with the data/observations.