General notes regarding lab reports:
- Never use the words “I” “we” “our” “my” “the student” “the experimenter” or any other word referring to you directly (this includes the use of “one” which should ALSO never be used). It makes your paper appear unprofessional. Instead of writing “I added 5.0g NaCl to 50mL water” just write “5.0g NaCl was added to 50mL water.” Whoever is reading your lab KNOWS you and/or your partner did it… your name is on the cover page!
- Avoid the use of the word “it”- your goal is to be CLEAR and CONCISE.
- Samples are "prepared" and graphs are "generated" or "produced" in the lab- nothing is ever "created."
- Although it IS permissible to use the word "weight" instead of "mass," NEITHER should be used as a verb. Masses may be "taken" or "found" or "discovered", but chemicals should not be "massed" (used incorrectly more and more frequently) and absolutely never "weighted."
- “Mole(s)” is like “dozen(s)” in that it is a number. Thus, “the number of moles of chloride” or “the amount of chloride” can be determined, but statements such as “the moles of chloride” make no sense grammatically or chemically.
- Tests are not “done” and samples are not “determined.” They are "spectra," not "graphs."
- No colloquialisms. You can still be funny and lightheated if that’s your style without being unprofessional.
- No contractions. Again, this is formal writing.
- Do not attempt to B.S. your way through a lab report...if you don’t understand the material, seek help!
- The confusing misuse of big words is NOT eloquent. You just sound like a dumb politician trying to sound intelligent.
- Expressing yourself so that the reader "kinda gets what you mean" is not sufficient.
- PROOF READ!!! Read your lab OUT LOUD...if it makes no sense, re-write it!
- Reading OUT LOUD is a lost art from which a great many of you could benefit.
- All data must be expressed with the correct number of significant figures.
- This is not the third grade, when you (hopefully) stopped writing “the subject of my book report is…” so NEVER use the phrase "in this experiment" or any equivalent thereof ANYWHERE in your report.
- Spelling and grammar errors are not acceptable. There are these really cool things called computers now where all you have to do is press one button and the spelling and grammar of your document are checked. You cannot possibly be too lazy to use it. Yes, the computer will find words and phrases that it doesn’t understand which you wrote correctly. You can simply tell the computer to ignore those. But it will also find your legitimate errors. Watch especially the use of “affect/effect,” “it's/its,” “their/there,” “passed/past,” etc. Whether or not English is your native language, it IS the internationally accepted language of science. USE your school's writing center! They’ll proof read your paper for FREE!
- Verbs should not be used as adjectives in an effort to economize your writing. It just makes for awkward writing. For example, “the samples were obtained” is correct, while “the obtained samples” is incorrect.
- Are the words “previously prepared” or “aforementioned” in your report? Chances are they are unnecessary. Remove them.
- Many of the things you use in the lab are precision measuring devices. Thus they are "instruments" not "machines." Do not use the latter word. That being said, YOU are operating the instrument, thus "an IR spectrum was acquired using a SmithsIR" is correct, while "the graph was measured by a SmithsIR machine" is incorrect for no less than 3 reasons. You can quantify something "via" a technique, but using "by" the technique makes it sound like the technique did it all by itself.
- Sample calculations must include 1 complete set of calculations using real data from the lab. The set of calculations must also include the propagation of error, if required. Include all units. If the units of the answer don’t match the calculation, the math can not possibly be correct.
- Express numbers in correct scientific notation with superscripts (3.0x10-6 NOT 3.0E-6 or 3.0x10^-6). These computers are amazingly adept at superscripts whereas old typewriters were not.
- Justify everything. If you say one method is better than another due to cost, the dollars involved had better be cited. All error must be explained.
- Be specific.
- Redundancy is not good. This includes repetition both within and between sections of your report.
- “Within” is correctly used above. Samples are not “within” a solution. Precise and accurate scientific writing is required.
- Redundancy is not good. (annoying, isn't it?!?!)
- The states of matter (s), (aq), (g) are NOT subscripted. (You may italicize the letter if you are so inclined.) The numbers in formulas denoting multiple atoms or functional groups ARE subscripted. Ex: AgNO3(aq).
- Watch Out For Unnecessary Capitalization… This Is Really Not A Good Idea When Writing A Report Filled With Chemical Symbols. Chemical techniques, e.g.- mass spectroscopy, may use capital letters for their abbreviations (e.g.- MS), but are not capitalized when written out. The only exception to this rule is in the report title. Table captions are not an exception (this is the one and only difference between these instructions and The ACS Style Guide- I choose to make this rule because inexperienced writers have proven incapable of deciding what words are important, and unacceptable inconsistencies generally result). Be sure abbreviations are correct, too: mL, mol, etc.
- Every single one of these could be in ALL CAPS, bold, italics. They are all critical to your development of superior scientific writing skills. Follow them or suffer the consequences. In cases where there is a discrepancy between this material and your lab manual (or what your teacher/professor has told you), you should consider the significance of the difference and who will be reading and grading your report.
************ BEGIN SAMPLE ORGANIC CHEMISTRY LAB ************
Acetylation of Salicylic Acid
With Acetic Anhydride
(Don’t just copy the title from your lab manual.)
(Also, note that “Determination of Aspirin” makes no sense, scientifically or grammatically. WHAT did you determine about it? Note the following appropriate definition of the word “determination:” The ascertaining or fixing of the quantity, quality, position, or character of something: a determination of the ship's longitude; a determination of the mass of the universe.)
Kevin Kolack, Ph.D.
Ch353, Section 3554
April 1, 2011
************ PAGE BREAK ************
Table of Contents
|Results and Discussion||7|
|Acknowledgments (no “e”- see your lab manual)||8|
|Appendix I- sample calculations||10|
|Appendix II- IR data (note that "spectra" is the plural of "spectrum" and that spectra (not "graphs") are acquired using a "spectrometer" or "spectrophotometer" (the model number of which should be noted in your experimental section), which is an "instrument" (not a "machine"))||12|
************ PAGE BREAK ************
Salicylic acid was combined with acetic anhydride and catalytic phosphoric acid to afford acetyl salicylic acid (Scheme I) in 90% yield. Product identity was confirmed by melting point (133-134oC) and infrared spectroscopy (lack of aromatic hydroxide signal, presence of ester carbonyl), as well as a successful FeCl3 test, indicating a high level of purity of the product.
Scheme I. Aspirin synthesis from salicylic acid.
THE ABSTRACT IS WRITTEN IN PAST TENSE. IT IS A BRIEF SUMMARY OF THE PROBLEM, PROCEDURE, RESULTS, ERROR, AND EXPLANATION. RESULTS ARE REPORTED AS ± THE STANDARD DEVIATION. IF BEING CALCULATED, THE PROPAGATED ERROR IS ALSO NOTED, SEPARATELY. (THINK OF WHY!)
See your lab manual and/or a statistics book for a discussion of significant figures, especially with regard to standard deviation.
Note that a percent error for a melting point has abolutely no significance and should never be reported... For example, an experimental melting point of 1 degree for a compound with a melting point of 2 degrees would have a 50% error, while an experimental melting point of 99 for a compound with a melting point of 100 would only have a 1% error. Both are low by 1 degree, and given similar melting point depression constants, would have similar levels of impurities. Don't perform calculations without thinking about their significance!
************ PAGE BREAK ************
Willow bark has been known to alleviate headaches and other pain for centuries. Hippocrates wrote of its curative powers as early as 400 BCE.1 Studies on willow bark led to the dicovery that the active ingredient is salicylic acid (SA), which was first synthesized in 1853 by Charles Gerhardt.2 Since SA causes upset stomachs for many people, a method of obtaining a milder product with similar curative powers was an area of intense research. The acetyl derivative, acetylsalicylic acid (ASA), was synthesized in 1893 by Felix Hoffman, which began being sold under the trade name "aspirin" by the Bayer Company several years later.3 The phosphoric acid-catalyzed conversion of SA to ASA using acetic anhydride involves the conversion of a phenol to an ester. This reaction is reversible, which is why aspirin commonly smells of vinegar, as the ASA hydrolyzes in air back to SA and acetic acid.
Iron(III) chloride (FeCl3) reacts with phenols to form brightly colored complexes, thus providing an excellent means for testing the effectiveness of the ASA to SA conversion. (ASA does not react because the phenol group is acetylated. ETC ETC ETC
PRESENT TENSE. BRIEF HISTORY AND TECHNIQUE OVERVIEW, INCLUDING WHY THE EXPERIMENT IS BEING PERFORMED (OR WOULD BE PERFORMED IF THIS WERE NOT JUST FOR A GRADE IN A CLASS). So, this lab report should include: theory of standard solution preparation including the reasons for the standardization of NaOH and amphoteric nature of KHP; reason for over-titration and back-titration; questions from manual. MUST INCLUDE REFERENCES TO CURRENT PERIODICALS, NOT JUST TEXTBOOKS. THIS SECTION IS NOT JUST A VAGUE RESTATEMENT OF THE EXPERIMENTAL SECTION!!! If this were a synthetic organic chemistry paper, the reaction mechanism would go here.
PAST TENSE. WHAT DID YOU DO EXACTLY? SOMEONE OF SIMILAR TRAINING SHOULD BE ABLE TO REPEAT THE EXPERIMENT USING THESE INSTRUCTIONS AND OBTAIN YOUR RESULTS. YOUR LAB MANUAL MAY NOT SAY TO INCLUDE DATA HERE, BUT THIS IS THE METHOD I CHOOSE TO FOLLOW TO AVOID REDUNDANCY WHEN PROVIDING RESULTS AND DISCUSSION. A RESULT IS DIFFERENT FROM DATA ACQUIRED DURING THE EXPERIMENT WHICH LEADS YOU TO THE RESULT.
Results and Discussion
(WHAT DID YOU DISCOVER?)
SPECIFIC SOURCES OF ERROR MUST BE NOTED, NOT GENERALITIES SUCH AS "THE BALANCE MAY HAVE BEEN USED INCORRECTLY"... IF THE BALANCE WAS USED INCORRECTLY, IT SHOULD HAVE BEEN NOTED IN YOUR NOTEBOOK AND THEN MENTIONED IN THE EXPERIMENTAL SECTION... (IF YOU'RE GOING TO TALK ABOUT THINGS THAT MAY HAVE HAPPENED, YOU MIGHT AS WELL SAY THAT A MONKEY STOLE YOUR PRODUCT, THAT SUNSPOTS CAUSED THE ERROR, ETC.) THE RESULTS OF THIS ERROR SHOULD BE DISCUSSED IN THE RESULTS SECTION. AND DON'T FORGET A CONCLUDING THOUGHT TO THE STORY THAT IS YOUR REPORT.
Acknowledgments (note the correct spelling of the word)
DO NOT thank your professor or the stockroom for doing their jobs, your lab partner for being your partner, or your roommate for putting up with you and letting you use their computer. While your gratitude is appreciated, it is unnecessary and unprofessional. (This, and much of the information presented here, may differ from what is stated in your lab manual or class. You should consider who is grading your report in deciding how to write it.) If someone was particularly instrumental in helping you with equations, etc, they should be mentioned here. If your professor stimulates you into pursuing a graduate career in chemistry (or discourages it, for that matter!) then (s)he may be mentioned here.
Textbooks, the lab manual, AND CURRENT JOURNALS should be consulted. The "references" section is for items which you "footnote" in the text. WEB PAGES SHOULD NOT BE USED (with the exception of the online versions of printed materials) as they are neither static nor peer-reviewed. MANY OF YOU HAVE NEVER USED ANYTHING OTHER THAN GOOGLE FOR RESEARCH UP TO THIS POINT IN YOUR EDUCATION... THAT IS VERY SAD. GOOGLE DOES NOT PROVIDE AN EXHAUSTIVE EDUCATIONAL OR SCIENTIFIC SEARCH. Online research can be useful in locating reference data, but caveat emptor- the base source should be cited and you should verify that the material you are citing is actually in the base source. (ie- How you found the source is irrelevant, but claiming that "the internet said the info was in that source" when the information is not, or the source doesn't exist or is incorrect, is a great way to get your paper rejected.) An "articles consulted" or bibliography section may be included for reference materials you used but which you do not directly reference in the text of your report, though this is nonstandard. The references should be in the following format, per The ACS Style Guide . Please note that different journals have different standards- there is no universal agreement on reference format, but you should use ACS format. If you don't want to buy the book, the references section is available online for free (as of 9/2011).
AuthorLastName, AuthorFirst(andMiddleIfWanted)Initial; OtherAuthorLast, OtherAuthorFirst. TitleOfBook, 1-WordPublisher: CityofPublication, YearOfPublication, PageReferenced.
AuthorLastName, AuthorFirstInitial; OtherAuthorLast, OtherAuthorFirst. TitleOfJournalAbbreviated, YearOfPublication, Volume:IssueNumber, PageReferenced.
journal accessed online
AuthorLastName, AuthorFirstInitial; OtherAuthorLast, OtherAuthorFirst. TitleOfJournalAbbreviated, YearOfPublication, Volume:IssueNumber, PageReferenced. URL (accessed Month Day, Year)
Kahn, O. Molecular Magnetism, VCH: NY, 1993.
Wang, S.; Tsai, H.-L.; Hagen, K.S.; Hendrickson, D.N.; Christou, G. J. Am. Chem. Soc. 1994, 116, 8376.
Brown, H.C.; McDaniel, D.H.; Haflinger, O. in Determination of Organic Structures by Physical Methods; Brand, E.A.; Nachod, F.C., Eds. Academic: NY, 1955, Chapter 14.
Wang, S.; Tsai, H.-L.; Hagen, K.S.; Hendrickson, D.N.; Christou, G. J. Am. Chem. Soc. 1994, 116, 8376. http://www.acs.org (accessed September 11, 2011)
Appendix I- sample calculations
(BE ABSOLUTELY SURE SOMEONE LOOKING AT YOUR PAPER CAN UNDERSTAND AND REPEAT WHAT YOU DID!!!!!)
Preparation of standardized NaOH solution
500mL of 0.1M solution desired
assume each NaOH pellet weighs 0.1g
(0.1mol NaOH/L solution)*(0.5L solution)*(40.01g NaOH/mol NaOH)*(1 pellet NaOH/0.1g NaOH) = 20 pellets NaOH needed
assume titration with approximately 25mL KHP solution
since KHP is a monoprotic acid, assume 25mL of 0.1M KHP (1 mol acid neutralizes 1 mol base)
(0.1mol KHP/L solution)*(0.05L solution)*(204.22g KHP/mol KHP) = 0.51g KHP needed