You are required to keep a laboratory notebook, partly as your personal work record to aid in completing the experimental write up and partly to learn how to maintain a good set of laboratory notes.A good record of your laboratory work may mean the differenced between keeping and losing a position in industry.Additionally it is often not the smarter person who solves a problem but the person who keeps better notes.The format described in the following is roughly consistent with industry and academic laboratory standards.Since your projects cover multiple weeks you may inter mingle prelabs with observation summaries of what you have done up to that point as part of a larger set of experimental work.
Your notebook must be permenentlty bound and written in ink. No spiral bound books allowed. For my 300 level and below labs duplicat copies are kept for security reasons, both yours and mine. You may use a duplicating notebook or photocopy pages of a non duplicating book for me. For 400 level labs you may use any style of bound notebook you choose except a duplicating note book. The pages should be numbered consecutively.Each experiment will consist of three main sections.A PRELAB section a DATA AND OBSERVATIONS section and a RESULTS/DISCUSION Section
Use of the first person singular is generally frowned upon in notebook (I weighed out 0.25 g of solid; I filtered the solution) and the third person passive preferred (About 0.25 g of solid was weighed out,the solution was filtered) the former style is now accepted in special cases when the third person passive is too wordy or cumbersome. In this course we will use the third person passive unless otherwise stated.
A.PRELAB
"Chance favors the prepared mind." -Louis Pasteur-
Ask any experienced
person involved in research science and they will tell you that one
hour
in the library in preparation will save many hours in the lab.With
this in mind this course will try and develop good habits for proper
preparation
for an experiment.For each experiment
you will prepare and turn in a PRELAB.While
this will require a significant amount of time to complete former
students
admit that it is time well spent because the laboratory time goes much
smoother.The prelab
must be turned in to your instructor by 8:00 AM on the day of the
laboratory.You
must have a prelab turned in before
starting
an experiment.
1.At
the top of every page
Name and lab sectionExperiment
TitleDatePage
number.
Professors receive a lot of paper this information will keep yours organized on my desk.Titles may be abbreviated after the first page. A sample of the first four sections of an experiment is attached to the back of the syllabus
2.Summary of Experiment:This should be a brief “word description of what you plan to do,Stating named reactions and the names of any special procedures of reactions (nitration, hydrogenation, etc.) or special apparatus (Melting point apparatus, TLC plates Chromatography columns, etc ) but not routine glassware such as beakers, flasks, filter, and the like.
A common mistake is to write about experimental details in the wrong section such as thesummary section or the results discussion section.For example, inclusion of specific details that are redundant with the EXPERIMENTAL PROCEDURE, or OBSERVATIONS/DATA SECTION will result in the loss of points.
A summary should contain only the most generalized features of the experiment.In the case of TLC these would be features that are relevant no matter what type of mixture you are analyzing, what type of TLC plate you are using, or what solvent is used to develop the plate.
The same principles hold true for the results/discussion section.Experimental details that are in the Observations/data section or in the source referenced by this section should not be repeated unless you want to discuss the effect of varying some experimental parameter.For example the effect of changing from 50:50 to 60:40 hexane:ethyl acetate as a developing solvent.
3.Experimental goals State unique aspects of the experiment in terms of goals.Examples:
To separate a mixture by Thin Layer Chromatography
To isolate cytochrome C
To make methyl esters of triglycerides
4 REACTION EQUATIONS/MECHANISMS/DIAGRAMS OF SPECIAL APPARATUS.Equations should be concise and show conditions, temperature, solvents, time, pressure, etc above and below the arrowDiagrams should be hand-drawn and clearly labeled.Artistic ability is not graded clarity is.Example while it is not absolutely essential to write names of compounds under each structure it is useful to you and the reader.
5.CHEMICAL DATA TABLE This should be set up as a tabular grid usually landscape on the page to give you enough room for all the columns which should be titled with the headings below.Buffers should be listed as both a buffer and the component parts that are required to make the buffer.Place the buffer name above the list of ingredients and then indent the ingredients
a.Chemical name and structure or formula for all chemicals Structures and formulas not required for proteins used:Starting materials (reactants), solvents, products and byproducts standards.
b.Physical state at room temperature and 1 ATM pressure, normal laboratory conditions Enter s for solid l for liquid and g for gas including solvents.This lets you know what type of material you are looking for.
c.Boiling
Point (bp) or Melting Point (mp). if
appropriate (solvents usually) give the pressure in mm Hg or torr
if not at 1 ATM (760 torr).
d.Quantity
of material called for in grams milligrams or milliliters.Use
SI abbreviations.
e.Molecular weight or formula wt. of reactants and products but not solvents or catalysts.
f.Molesif actually consumed or produced in a synthetic reaction, again not solvents.For synthetic products give the theoretical yield in both grams and moles assuming 100% conversion.
g.Flammability State yes or no if available give flash point in oC
h.Waste category for each material used solvents included.Assume you have to dispose of a few grams of each of the listed chemical substances.How should this be done?In this column enter the following codes according to the correct channel for disposal:
NHO= Non-halogenated organic waste container
HO=Halogenated organic waste container
HM= Heavy metals waste container
D= Drain disposal with plenty of water
WB= Waste Bin for dry non hazardous solids such as NaCl sodium sulfate alumina
It
should be noted that mistakes in this column will result in large point
deductions!If you don’t know ask.
i.Toxicity give specific information i.e. corrosive , irritant,highly toxic, cancer suspect
Optional data that is useful
j.Price for the smallest quantity sold or the starting materials only.Do not include solvents.
k.CommentsOther noteworthy properties useful in handling the material such as, hygroscopic, oxidizer moisture sensitive or information of suppler if it’s unusual
The most complete source of this information is
the
Catalog Handbook of fine Chemicals from the Aldrich chemical Co.Your
laboratory manual contains much of this information as well.Other
worthwhile references are the CRC Handbook of Chemistry and Physics,The
Merck Index and the Lancaster Laboratories Chemical Catalog.
6.PRELAB EXERCISE when asked for in an
experiment
7 PROCEDURE This is the final portion of the prelab and the most important.All students must have a signed procedure before they start work.The procedure should contain a step by step translation of the narrative procedure in the text.The text will note be allowed on the laboratory desk!!!It is useful to leave space in the procedure for recording data while in the laboratory.One method is to divide the page vertically and use half the page for writing the procedure and half for recording data.Many lab manuals have placed a vertical line on there pages just for this method.Inserting empty tables in the space across from the instruction where you would perform the work is an excellent habit.The second method is to insert tables and leave space within the procedure itself to record information.You must reference the source of the experimental procedure details, the handout or the text, a journal or book publication in the research setting, because the person who would want to duplicate your work will need to refer to this.The best criterion for judging the amount of detail is:Can another student replicate your work using your notes?You should assume that the student has had some lab experience and would know some manipulation.For example a second semester student would not need a description for taking a melting point
THE FOLLOWING SECTIONS MAY OR MAY NOT MAKE SENSE TO INCLUDE IN YOUR PRELAB.IF IT MAKES SENSE DO THEM.
8.CHROMATAGRAPHIC BEHAVIOR.this is a comparison of the starting material and expected product and side products.consider using thin layer chromatography to separate the starting material from the products expected and predict which would have the higher Rf based on molecular polarities as predicted from the compounds structure and functional groups.Look at your TLC experiment from last term to help with this.
9Spectral – FEATURES COMPARISON OF STARTING MATERIAL AND PRODUCT.For your particular reactions determine whether IR and NMR can be used to easily differentiate between starting material and product and describe major spectral features of absorbance’s that would be different when comparing starting material to product.In some cases they will not be useful.If this is the case state why this is so and give a brief explanation.Utilize the chapters in your classroom text for this work.Do your best to predict what you would expect to change in the spectra from reactants to products.You do not need to look up the spectra to do this and I would discourage you from that practice.
10 EXPLANATION OF PRODUCT ISOLATION AND PURIFICATION OR “WORK UP” Give a short explanation of the product isolation and purification procedure often called the “work up”.Explain why a particular operation, extraction distillation, recystalization, filtration was carried out in terms of what by-products are removed and what is isolated.Give the physical property(ies) that allow for there removal or separation at each pointing the isolation and purification scheme.
11Buffer and assay tables:When making solutions it is handy to use tables to enable you to change the volumes that you need easily if the need arises.
A sample table is given below for both a buffer and an assay often for buffers you will need to leave space for adjusting the pH with an acid or a base this is not shown.
Table 1:Phosphate
buffered saline
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KH2PO4
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K2HPO4
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NaCl
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Milli-Q
H2O
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Table 2:Assay
for concentration of Enzyme
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Buffer needed
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Enzyme neede
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FINAL REPORT
OBSERVATIONS/DATA
or In-Lab section
Within the procedure section your notes should contain an accurate, concise record of the steps you carried out and what you observed in the laboratory as you did it. when you weigh out a chemical to add to a reaction, you should record how much was added and describe the way you added it, slowly over five minutes or all at once.If a color change occurs or a gas evolves, write this down.You need to record the things your observed:weights volumesbubbles heat given of crystals precipitating , solvent running up a tlc plate, spot migration distances, solvents, boiling points, how you monitored the reactions progress, comments on isolations of products and left over reactants, and more.If you used an instrument describe how you used it and the settings that you employed.
Make entrees into your notebook and not on scraps of paper for later entry into your notebook.Scraps of paper blow away or get thrown away and you may lose important information when an over zealous instructor cleans up the laboratory.Your observations are critical so do not be afraid to make them.How ever be sure of what you observe.For example, record that a gas was evolved rather than H2 was evolved unless you tested the gas and found it to be H2 of course.You may make assumptions you just need to make it clear that it’s an assumption, but it is a bad habit to get into better to state what you might test for to determine the nature of an observation.
An example observations date section is shown below.Italics indicate what was recorded during the laboratory session and regular type identifies what was written as pre-lab.
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Jane Webemo
Section
35
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Exp 1 recrystallization
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18 Jan 2006 Page 4
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Procedure/Observation/DATA:
Expt. 1Finding a Recrystalizing solvent for my unknown
Tare reaction tube6.467
g wrote weight of
tube with diamond pencil
Obtained Unknown
#108
Weigh out approximately 10 mg
Actual 13 mg of
unknown
First solvent choice for solvent will be water
Attempt to dissolve in 0.25 ml of distilled water in reaction tube.
Solid
did not dissolve in water at room temperature
Add a boiling stick and heat to boiling and agitate for a least 1min.
Still did
not dissolve completely even after adding 0.25 ml more of water
and heating
for another min.Some of the material
does seem to have dissolved but notallSet
aside.
.
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Jane Webemo
Section
35
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Exp 1 recrystallization
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18 Jan 2006 Page 5
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From Page 4
Second solvent choice will be 0.25 ml of ligroin
Weigh out approximately 10 mgActual 9 mg of unknown
Attempt to dissolve
in 0.25 ml of ligroinin
reaction tube.
the
sample dissolve immediately at room temperature Ligroin is no good.
Add a boiling stick and
heat the sample with agitation for 1 minute
Noticed crystals forming on the stick in the
water
solution will go back to water
Added another
0.5 0.25 ml of water to the 0.5 ml in the tube and
heated
with agitation --- the material
bumped will need to repeat the experiment.
Weighed out
11 mg of unknown, added 0.75 ml of water and heated with agitation and
a new boiling stick for 2-3
min all the material dissolved. Set aside
When cool
crystals formed Water is solvent of choice for recrystalization
about.75 ml/10 mg
of material
Note the single line cross out of the mistake and the procedure that was not followed you can still read what was not performed and the mistake.
What follows is what you might find towards the end of a crystallization experiment.
Weight of unknown
and Rxn Tube6.231
Rxn
tube tare 6.193
Net amount of
unknown recovered 0.038
g or 38 mg
Percent
Recovery (38mg/68 mg)*100%= 56%
Note that space must have been left for other work to take place before this table, but that part of the table is pre-written.Also note that the results are written in a style called gross tare net.
C RESULTS DISCUSSION or Post Lab section.
Conclude each experiment with an analysis of your results.Give any special information of graphs requested in the manual or as asked for by your instructor.as required report your observed melting point or boiling point,physical appearance, and percent yield (show calculations)., and highlight the data so that it easy to find by separating it out on the page not with a highlighter.Tabulate any multiple data readings ( Rfsmp, retention times distillation volumes, weightswavelengths or wave numbers in neat legible column s or tables.Answer the questions Where the goals of the experiment achieved?, Was the desired product made?,: and How was it characterized?
As with the Summary section of the PRELAB,Details that are in the experimental procedure should not be repeated unless you want to discuss the effect of them on the final results.See the example in the pre lab section.
This section of the laboratory should also contain your comments and conclusions regarding the experiment.For the techniques experiments you should. discuss how experimental parameters or physical and chemical properties such as solubility, boiling point, type of distilling column, purity, polarity, pKa, type of developing solvent, etc affect the outcome of the experiment.State how your data supports these ideas.For synthetic reactions you should discuss any significant problems and if you yield was lower than expected, what might be the reason(s) and what could be done to improve the yield if you repeated the reactions.You should also discuss how the data you acquired verifies that you have indeed isolated the correct product and not a by-product or starting material.Be sure to note what instrument you used and all the settings you employed.
If you acquired a spectra draw the structure and show assignments of major spectral assignments directly on the spectra attach the spectra to the pages of the completed experimental report that you turn in.
Answer any assigned questions at the end of your experimental report.
It is a good idea to put together a quick outline of what you want to include in your RESULTS/DISCUSSION section before you start writing.you will find this actually saves time because you avoid being redundant and avoid extraneous information.The skills necessary to summarize a piece of work as a concise, readable final report will be required in essentially all future employment be it nursing, research, medicine, or engineering.Take the opportunity that this course offers to practice and improve these skills.
As each PRELAB or FINAL REPORT for a particular experiment is due according to the schedule you will remove the original white pages from your note book staple them together and hand them in.After grading the PRELAB will be handed back and you should staple the FINAL REPORT to the back of this.You will need to insert prelab pages back into your note book to record data during laboratory exercises.In many cases spectral data and products will be attached according to the instructions given.
10% of the
grade will be deducted for every day that work is late beyond the due
date
(this includes weekends 2 days)