The Laboratory Notebook: Instructions and Guidelines

Transcription

1 Chem A225L The Laboratory Notebook: Instructions and Guidelines The lab notebook will determine a significant part of a student s course grade; students should keep it with them at all times when working in the laboratory. All of the following directions should be followed carefully; it will also be helpful to periodically review the following guidelines. Before the first experiment, please complete the following directions: 1. Purchase a lab notebook. The notebook should be a hard-bound composition book. 2. Label the front cover of the notebook in the following format: LABORATORY NOTEBOOK Student s Name CHEM A225L Spring, Label the inside front cover of the notebook in the following format: IF FOUND, PLEASE RETURN TO: Student s Name Student s Phone Number Student s Address (optional) 4. On page 1, prepare an index. Label the table of contents as follows: TABLE OF CONTENTS CHEM A225L Spring, 2017 Student s Name Drawer Number: ## 5. Below the title of the index page, draw and label six columns as follows: DATE PRE-LAB APPROVED INSTRUCTOR INITIALS EXPT # AND TITLE DATE COMPLETED INSTRUCTOR INITIALS PAGES General Notebook Guidelines The following general guidelines should be observed throughout the semester. These are presented in no particular order. All are important. Following the guidelines described here and elsewhere will help maximize points earned on the notebook. Failure to follow these guidelines will result in lost points. It strongly recommended that students frequently review the guidelines in this handout throughout the semester. 1. Use only waterproof, indelible black or blue ink to write in the notebook. Do not use red ink. 2. Errors should be crossed out with a single line and the correction written nearby. Do not use whiteout. Do not remove pages. 3. Number the facing pages only using ODD numbers in the upper right-hand corner. 4. The first experiment should begin on page 5. Leave pages 1 4 blank for the Table of Contents. All experiments should be started at the top of a blank facing (odd-numbered) page. 5. Data should be recorded in directly in the notebook as it is collected. Data should never be recorded on separate sheets of paper to be copied later into the notebook. The instructor will dispose of any such sheets that are found.

2 Chem A225L The Laboratory Notebook Page 2 6. Procedures should be recorded in the notebook as they are performed. Observations should be recorded with the procedures at the same time. Students should not skip recording procedures, or wait until after lab or another day to record procedures. Remember, fabricating lab data outside the lab is a serious academic offense and will be severely punished. 7. At the end of a days experiments, students should draw a line and print (date) & (time) at the conclusion of lab work in their Procedures and Observations section. The notebook should then be presented to the instructor to be initialed. If the procedure is continued on a subsequent day, the date should be recorded before any additional entries are made. Tables present a special problem if data is collected on different days; therefore, all tables of data and observations MUST include an additional column entitled Date Recorded. 8. The Table of Contents should be kept current at all times. Make new entries at the time an experiment is started. Complete entries immediately following completion of the Conclusion of an experiment. 9. All statements made in the notebook must be truthful and accurate. Dry-labs, exaggerated yields, and falsified data are all considered instances of academic dishonesty and will result in penalties in accordance with the academic honesty policy of the course. 10. The lab notebook must be turned in at semester's end to receive a passing grade in the class. 11. Reserve a full page for chromatograms, spectra, or handouts. Do not tape chromatograms, spectra or handouts over data or observations, instead, tape them to a blank page. The blank pages may be at the end of the experiment, following the conclusions, if no space was made for them earlier. 12. Taped-in pages should be folded in the middle so that they do not protrude beyond the edges of the notebook. Then, the page should be taped on one edge close to the spine of the notebook so that it can be folded out for observation. Under no circumstances should there ever be loose chromatograms, spectra, TLC plates left loose in the notebook. ORGANIZATION OF EXPERIMENTS The organization of a given experiment will vary with the experiment. Often, one or more of the following sections will not be applicable to a given experiment. However, all experiments must at least include the following sections: Date, Title, Reference, Introduction, Haz-Mat, Procedure and Observations, and Conclusions. The following list details all of the possible sections which might appear in an experiment, along with some instructions for how to complete each section. They appear in the order in which they should normally appear in an experiment. Each of the following sections should be indicated with a heading in the lab notebook, and the heading should be in a box. Pre-Lab Sections The following sections should be completed before coming to the laboratory. The instructor will check and sign-off the pre-lab before the student will be permitted to start the lab. Students who come to lab unprepared might be sent out of the lab to complete the pre-lab before being allowed to work on the experiment. DATE The date that the experiment was first entered into the lab notebook. This may be several days before the actually experimental procedures were performed. TITLE The title should have the following format: Lab ## : title. All of the words in the title should be capitalized.

3 Chem A225L The Laboratory Notebook Page 3 REFERENCE A reference for the procedure should be cited. The lab text should be cited as follows: Pavia et al., Introduction to Organic Laboratory Techniques: A Microscale Approach, 3rd Ed. pp. ## ##. (Note: in handwritten text, words that should be italicized are underlined instead.) Handouts should be cited as follows: Handout, title, Chem 226, Orange Coast College, Fall CHEMICAL EQUATION For preparative experiments, the chemical equations should be written for the desired observed reactions. Each equation should be written on a separate line. The equations should feature structural formulas, and each structure should be labeled with the appropriate name. The structures of isolable intermediates (even if the intermediates were not isolated) should be shown. REACTANT TABLE In preparative experiments, an important part of the planning process is determining the identity and quantities of the reactants. This is conveniently done in a table called the Reactant Table. The format for the reactant table will be detailed in a separate handout. THEORETICAL YIELD CALCULATION In preparative experiments, the theoretical yield of the product (in grams) should be calculated based on the quantities proposed in the REACTANT TABLE. SEPARATION SCHEME For most experiments, a flow-diagram should be included which outlines how the product is isolated, separated, and/or purified. An example is shown on p. 24 of the lab text Clearly indicate any separation techniques and any chemical changes that occur during separation. The separation scheme should illustrate any chemical changes with the appropriate structural formulas. Once a structure is illustrated, it may be abbreviated until changed again. PRE-LAB QUESTIONS Most experiments will have several pre-lab questions to be answered in the lab notebook. These will be found on the supplemental handouts for each experiment. These questions should be answered in the order presented on the handout. The entire question should be written out in the lab notebook, then the answer should be written below in complete sentences.

4 Chem A225L The Laboratory Notebook Page 4 During the lab period: PROCEDURE AND OBSERVATIONS This section should be organized in two columns. It may help to draw a line down the page to separate the columns. A sample is shown below. The left column is the Procedures column. It should cover about 2/3 of the width of the page. In this column, the procedure followed will be detailed in numbered steps. Procedures and Observations should be recorded as the experiment is performed in the laboratory. Enough detail should be recorded in the procedure so that the experiment could be duplicated by a person using the procedure as their only reference. The date should be recorded at the top of the PROCEDURES section before any procedures are documented. The PROCEDURES should be written in numbered steps at the time the procedure is executed in the lab. It should describe what was actually done, not what was planned. Any mistakes, such as spills or starting over, should be described in this section, so that it accurately describes the procedure actually executed in the lab. The second column is the Observations column, used to record observations and data. All data in the Observations column should be recorded with a number that corresponds to the numbered step in the procedure during which the observation was made. Data that are appropriate to record in the Observations column include: weights of any containers or reagents that are weighed; melting points; boiling points; diagrams of apparatus; observations of color changes; and any other observations of changes or physical properties. PROCEDURE AND OBSERVATIONS (date) 1. Weighed about 0.5 g of p-aminobenzoic acid on the balance and transferred to a dry 25 ml round-bottom flask. 2. Measured about 0.7 ml of absolute ethanol in a 10 ml graduated cylinder, then poured it into the 25 ml round bottom flask. 3. Added a boiling stone to the flask. 1. p-aminobenzoic acid is a slightly brownish/white powdery solid. sample+tare = g tare (weighing paper)= g sample weight g 2. Ethanol is a clear, colorless liquid. Most of the solid dissolved to form a slightly brown solution Measured about 0.5 ml of conc. H 2 SO 4 using a measuring pipette, then added it dropwise to the mixture in the flask. 4. As the acid was added, a white precipitate formed. A smoky vapor formed above the surface of the liquid. 5. Attached a water-cooled condenser and heated the mixture to reflux for 75 min in a boiling water bath. 5. (a diagram of the apparatus should be drawn here).

5 Chem A225L The Laboratory Notebook Page 5 After the experiment is completed: CALCULATIONS Many experiments will require calculations as part of the analysis leading to the conclusions section. These calculations should be detailed in this section with an appropriate sub-heading or label. Examples of subheadings include "Determination of Limiting Reagent"; "Theoretical Yield"; "Percent-Yield"; and "Percent- Recovered" (See page 26). If there is a repetitive calculation, then the algebraic formula should be listed first, then one example with actual data substituted in the formula, then a table listing the results for the example and the remaining data. If a GCanalysis is performed, have a sub-section titled "GC-Analysis" followed by the necessary calculations. For ALL calculations, include an algebraic formula or word expression before numerical substitutions. POST-LAB QUESTIONS Most experiments will have several post-lab questions to be answered in the lab notebook. These will be found on the supplemental handouts for each experiment. These questions should be answered in the order presented on the handout. The entire question should be written out in the lab notebook, then the answer should be written below in complete sentences. CONCLUSIONS The Conclusions section is the second most important part of the lab notebook. It provides a summary and analysis that links the Procedures and Observations to the objectives of the experiment. It should be completed as soon as possible following the completion of the experimental work. In laboratory research, the conclusions provides an opportunity to evaluate the success of a hypothesis, and it also is an appropriate place to suggest plans or further experiments. The Conclusions should be written as much as possible in complete sentences. Each experiment will have a unique organization for its conclusion; however, there will be several reoccurring themes. The Conclusions should follow this general format: The conclusions should start with a brief (1-3 sentences) summary of the experiment. The results from the experiment should be reported, including actual data from the experiment. Then, conclusions should be made, using experimental and literature data to support them. Each experiment is unique, but some appropriate topics for conclusions include: discussion of percent yield and purity, modifications to the planned procedure, suggested improvements to the procedure, and interpretation of spectral data. This is not an exhaustive list. Other topics may be useful or appropriate. Try to take some time when preparing the Conclusions to think about their organization and content, as well as the significance of the experiment and its results. Finally, any issues such as unexpectedly low yields or unexpected results should be discussed. A part of a sample conclusion is shown below: In this experiment, benzocaine was synthesized from p-aminobenzoic acid and ethanol using the Fischer esterification method of heating with acid catalyst. After cooling and adding aqueous base, the solid product was isolated by vacuum filtration. The crude product was purified by recrystallization from ethanol/water. About 0.49g (3.57mmol) of p-aminobenzoic acid was used; the weight of the purified product was 0.38g, which gave a yield of 65%. The melting point of the purified product was o C (literature value o C, from [Projects...] p. 101). (continue from there) Additional Guidelines for Procedure and Observations It is recommended that students frequently review these guidelines throughout the semester. 1. The Procedure and Observations should include a labeled and accurate diagram of any experimental apparatus that is used. However, if the same apparatus is used without modification in a later experiment it does not need to be drawn again; instead, it may be referenced by page number of the drawing.

6 Chem A225L The Laboratory Notebook Page 6 2. Describe the appearance and odor (when appropriate) of all reagents and unknowns. Remember to record the number of any unknowns are used. 3. Always indicate the type, brand, or model of any apparatus used. For volume transfers, indicate Pasteur pipette, syringe, calibrated pipette, etc. For filtrations indicate Buchner funnel, Hirsh funnel, filter-tip pipette, etc. Also indicate which apparatus was used for m.p. determination, b.p. determinations, IR, or GC. 4. When reporting melting point ranges or boiling points, record the temperature to the highest precision allowed by the thermometer (1 C or 0.1 C). Additionally, when measuring melting points, be sure to include a description of the behavior of the solid on melting.(softening, sweating, discoloration, etc.). 5. Be sure to describe the color and color intensity, if any, of all materials. Especially note color changes. However, be aware that color changes in organic chemistry are often not significant. Students should not be overly concerned about differences between their observations and their neighbors. 6. Be sure to note degree of clarity of all mixtures (clear, slightly cloudy, cloudy, opaque, etc.) Note any unusual appearance at the borderline between two liquid phases. Note if an emulsion is present. 7. Be sure to note time/rate of reaction/change. Students should record how long they mixed, heated, observed, etc. Semi-quantitative descriptions are good (briefly, slowly, immediately, quickly, etc.) but quantitative descriptions are best (approx. 15 s, 5 min., 1.5 h). 8. Describe the appearance of all solids collected as seen under the dissecting scope (in the balance room). Describe the crystal form, if any, of solids (needles, cubic, rhomboid, amorphous). 9. Attach any spectra or chromatograms directly to one or more pages of the notebook at the end of the experiment. Tape and fold spectra or chromatograms so that they do not fall out of the notebook and so that no part of the attached pages protrudes from the edges of your notebook. These pages should be folded so they may easily be examined (don't staple them shut). Be sure that all attachments are clearly labeled and identified as well as referenced in the procedure and observation section. 10. Extractions: When doing extractions, refer to both the type and position of each layer (for example, the top hexane layer, the bottom methylene chloride layer, the top organic layer, the bottom aqueous layer, etc.). 11. Distillation: When performing a distillation, give appropriate descriptions to the separated portions (for example, the original liquid mixture, the distillate, the first fraction, the second fraction, etc.). 12. GC: Column information, flow rate, amount and identity of injected sample must be recorded directly on the chromatogram at the time the chromatogram is obtained. If the cut and weigh method of analysis is used, do not cut the original chromatogram. Instead, make a good photocopy of the peaks, and cut and weigh the copy. 13. TLC: TLC plates should be accurately drawn actual size in the lab notebook (it is useful to trace around the plate, then draw the spots). The drawing should include the location of the solvent front and the location of the starting spots. The developing solvent (eluent) and the type of plate (silica gel, alumina, etc.) should be written above the drawing. The identity of the spotted material and the number of spots should be clearly indicated below each starting location on the plate. For each spot, clearly indicate the color and UV activity before and after iodine treatment, as well as the R f value of the spot. Be aware that TLC plates fade and change over time, so analyze and sketch a plate as soon as possible after it is developed. 14. IR Spectra: Several peaks of each IR spectrum should be analyzed as follows: the wavenumber measured for the particular peak should be printed immediately below the peak. Below this measured value, record in parenthesis the corresponding values from the spectrum of an authentic sample (if available). Below this, indicate whenever possible the probable origin of functional group peaks (O-H stretch, C-H bend, etc.). 15. Submission of Products: Any isolated products should be stored in a corked and labeled sample tube (not a small test tube). These test tubes should be stored in the lab drawer until called for by the instructor. Instructions for labeling materials are found on page 29 of the lab text. Follow these instructions carefully. At no time should there be unlabelled intermediate or final products in the lab drawers.