Organic Chemistry Lab: Improving Your Lab Report
by Dr. Zhiyong Wang and Dr. Gloria Pimienta
The following is a list of things you should bear in mind when you compose a lab report
using Microsoft’s Word program:
1. Use 12 point font with normal (1") margins on all sides.
2. Number all pages in sequential order.
3. The date shall be the actual date when your experiment was performed.
4. Separate sections with appropriate sub-headings (bold or italic); and staple all pages together.
5. Your and your partner’s names must be on the report in the following format:
XXX (your name)
Partner: YYY (partner name)
6. If it’s an experiment of technique (such as melting point measurement), show the chemical
structures for all the compounds you actually used in the experiment. If it’s a reaction, show the
reaction scheme but not individual structures in the first page. You must draw the
structures/schemes by yourself using appropriate software such as MarvinSketch, Accelrys, or
ChemDoodle. Direct copy of images from your eChapters, Internet or any electronic resources is
7. For reference specify the edition and full page range of the lab textbook. (This requirement is
different from the example section F on page 21 of the textbook.)
8. For scientific report the smallest details, such as punctuation, need to be as accurate and
correct as possible. Convention must be followed. The grammar must be checked. Each
occurrence of minor error will result in 5 points reduction. You will receive some leniency for
first-time mistakes, but each recurring minor error will result in full 5 points deduction.
9. All measured values must have an appropriate unit. Have one space between any value and its
unit, such as 132 – 133 oC. Use symbols/abbreviations for the units, such as oC instead of degree
Celsius and g instead of gram. Common units: g, mg, mol, mmol, mL, L, oC, mm, cm, m, h (for
hour), min (for minute), s (for second). The values should also have correct significant numbers.
Thus 0.1350 g (measured from a balance) should not be recorded as 0.14 or 0.135 g, and 1.04
mL (measured from a graduated cylinder) should not be recorded as 1.0 or 1 mL.
10. Chemical names are like other nouns. Don’t capitalize them unless they are at the beginning
of a sentence. Unlike elsewhere in a sentence, there should be no space after a comma in
chemical names, e.g. 1,2-dichloromethane. This is a convention for chemists. Similarly, it should
be “iron(III) chloride” but not “iron (III) chloride”. The atom symbols in chemical names needs
to be capitalized and italic, such as N,N-dimethylaniline. Prefixes such as “tert”, “meta”, “m”,
“ortho”, and “para” need to be italic as in “t-butyl chloride” or “m-xylene”, and they are not
capitalized at the beginning of a sentence, e.g. “m-Xylene was used...”.
11. Procedure: Rephrase the procedures in the textbook using past tense (the action was already
done) and passive voice (focus on the action not the doer) for the lab reports. This requirement is
different from the example section I on page 22 of the textbook. Quite often we made
omissions/additions/modifications to the procedures on the textbook, and in your lab report you
should write only the modified procedures. You can write up simplified steps for pre-labs (R on
page 25 of the textbook) but only normal paragraphs (see I-K on page 22) should be adopted for
lab reports. Wrong format in your Procedure section will result in 10 points deduction.
Wrong: Crush the sample into fine powder using a spatula. (instruction format, present tense)
Wrong: We crushed the sample into fine powder using a spatula. (active)
Correct: The sample was crushed into a fine powder using a spatula. (past tense, passive voice)
12. Observations: faithfully record what you actually did in the experiment. Any data (weight,
volume, temperature, time, etc.) and phenomenon (color change, cloud, smoke, bubbling, heat
generation, etc.) must be reported. Do not repeat what was already said in the “Procedure”
section, although you may have to briefly mention which part of the procedure it was in relation
to the observation. Report any accidents and spills. Past tense and passive voice should be used.
13. Yield calculation: for chemical reactions you must show the balanced equation, determine the
limiting reagent, and calculate the theoretical and actual yields. The quantity of the starting
materials should be what you actually measured (such as 76.9 mg) but not just what the textbook
says (such as 75 mg). The yields should be rounded to an integer, e.g. 53% instead of 52.88% or
52.9%. Yield calculation which is wrong or lacking details will result in up to 20 points
reduction. The yield you get will not affect your report grade significantly. Too high (> 100%) or
too low (< 30%) yield will result in 10 points reduction, in which case you should rationalize it
in the “Discussion and Conclusions” section.
14. The reaction mechanism should be drawn by software (such as MarvinSketch, Accelrys, or
ChemDoodle) if it has been discussed during our lectures or in in your lab textbook.
15. Discussion and Conclusions
You can include things like trends in the data, data interpretation, relevance of the
experiment or the technique, and what you have learned. To elaborate using an example:
Background material. Define melting range. What happens on a molecular level during
Data trends and interpretation. Any trends on the data? Is the data as expected? Explain
the theory and principle behind the expected trend in the data. If it is not, what are
sources of errors?
o The melting point (mp) we obtained for pure urea is which is close to the
literature value of
o Mixtures have lower mp and broader mp range than the pure substances because
. Our data is as follows:
and is consistent with this expected
What would be an application of this technique or data trend? (e.g. identification,
determination of purity)
Summarize the success (or failure) of the experiment. Describe what happened in your
experiment. Describe the interpretation of the results and their significance. Explain what the
results mean, what conclusions can be drawn, etc. Do not put excessive focus on yield. You can
simply mention your yield as low/high/moderate/reasonable and briefly discuss the possible
reasons for that outcome. Your data should be presented in the form of tables and graphs as
appropriate. All tables and graphs must be well-organized, numbered, and given clear descriptive
titles. (e.g. Graph 1. Mp-Composition Diagram for Urea/Cinnamic Acid Mixtures.)
Do not simply repeat your procedure and observations in this section. This is probably the
most important section of your lab report. Deficiencies in this section will result in up to 30
points deduction from your lab report grade.
16. A good discussion of lab report writing can be found at
http://www.professorkshow.com/sample-organic.html. If there is any contradiction to my
instructions as above, follow my instructions.
How to calculate the yield of an organic reaction?
Sample reaction: borohydride reduction of 2-methylcyclohexanone. Make sure you have the
balanced reaction written out:
The theoretical yield must be calculated based on the actual quantity of the starting materials
you used. If the textbook mentions something like “The residue should weigh about 150 mg”,
you cannot use that 150 mg as your theoretical weight of your product.
According to the textbook instructions, you should use 300 mg of 2-methylcyclohexanone and
50 mg of sodium borohydride. Let’s suppose you get 0.2343 g of product in the end.
Scenario 1: you indeed used exactly the quantities as indicated in the textbook.
2-methylcyclohexanone: 0.300 g ÷ (112.12 g/mol) = 0.00268 mol
NaBH4: 0.050 g ÷ (37.83 g/mol) = 0.00132 mol
Notice from the balanced reaction 0.00268 mol of 2-methylcyclohexanone would
consume 0.00089 mol of NaBH4. You actually used 0.00132 mol of NaBH4, so it is in excess
and 2-methylcyclohexanone is the limiting reagent.
The mole ratio between the products (a mixture of cis and trans isomers) and 2methylcyclohexanone is 1:1, so the theoretical weight of the products is:
2-methylcyclohexanol: 0.00268 mol × (114.18 g/mol) = 0.301 g
The actual yield you got is:
(Notice the example calculation M on page 23 of the lab textbook contains one error. It
should be 100% but not 100 in the equation.)
Scenario 2: you actually used 0.303 g of 2-methylcyclohexanone and 0.034 g of NaBH4.
2-methylcyclohexanone: 0.303 g ÷ (112.12 g/mol) = 0.00270 mol
NaBH4: 0.034 g ÷ (37.83 g/mol) = 0.00090 mol
Notice from the balanced reaction 0.00090 mol of NaBH4 would consume exactly
0.00270 mol of 2-methylcyclohexanone. So both starting materials are the limiting reagent.
If you choose to use NaBH4 as the limiting reagent, the ratio between the products to
NaBH4 is 3:1, so the theoretical weight of the products is:
2-methylcyclohexanol: 0.00090 mol × 3 × (114.18 g/mol) = 0.308 g
(If you choose to use 2-methylcyclohexanone as the limiting reagent, the ratio between
the products to 2-methylcyclohexanone is 3:3, or 1:1, so the theoretical weight of the products
2-methylcyclohexanol: 0.00270 mol × (114.18 g/mol) = 0.308 g)
The actual yield you got is:
Scenario 3: you actually used 0.303 g of 2-methylcyclohexanone and 0.030 g of NaBH4.
2-methylcyclohexanone: 0.303 g ÷ (112.12 g/mol) = 0.00270 mol
NaBH4: 0.030 g ÷ (37.83 g/mol) = 0.00079 mol
Notice from the balanced reaction 0.00079 mol of NaBH4 would consume 0.00237 mol
of 2-methylcyclohexanone. You actually used 0.00270 mol of 2-methylcyclohexanone, so it is in
excess and NaBH4 is the limiting reagent.
The ratio between the products to NaBH4 is 3:1, so the theoretical weight of the products
2-methylcyclohexanol: 0.00079 mol × 3 × (114.18 g/mol) = 0.271 g
The actual yield you got is:
x 100% = 86%
Your experiment will always fall into one of the above three scenarios when you run any twocomponent reactions. Make sure to show the calculation and reasoning process as above for your
lab reports. Wrong yield calculation will result in 10 points deduction from your lab reports.
Chapter 32: Friedel-Crafts Acylation of Ferrocene: Acetylferrocene
Background information for ferrocene:
Ferrocene is a typical example of sandwich compounds. It has two organic components
and one inorganic component. Its discovery by Pauson and Kealy at Dusquesne
Univeristy in 1951 (Kealy, T. J.; Pauson, P. L. "A New Type of Organo-Iron Compound".
Nature 1951, 168 (4285), 1039) largely inspried the organometallic chemistry, one
frontier field of modern organic chemistry. The compound inherits features from both
parents: super stable (aromaticity) and soluble in most organic sovlents while insoluble
in water (features of aromatic organic compounds), and highly crystalline (feature of
Ernst Otto Fisher and Geoffrey Wilkinson independently deduced the sandwich structure
of ferrocene and carried out further research on related compounds. They won the 1973
Nobel Prize in Chemistry for "their pioneering work performed independently on the
chemistry of the organometallic, so called sandwich compounds".
Purpose: 1) To perform and learn the Friedel-Crafts acylation reaction; 2) To use IR
spectroscopy to corroborate the structure of the reaction product.
First prepare a water bath of ~95 oC. Weigh ~93 mg of ferrocene and add it to a 10 x 100
mm reaction tube. Sit the reaction tube in a small (10 mL) Erlenmeyer flask on a balance, zero
the reading, add ~0.38 g of acetic anhydride, zero the reading again, and add ~0.17 g of 85%
phosphoric acid. Record the exact amount of chemicals on your notebook. Warm the tube in the
95 oC water bath while shaking the mixture periodically to dissolve the ferrocene. If you see big
chunks of solid use a stainless steel spatula to break apart and crush the solid. The process should
take no more than 5 minutes. Heat the mixture for an additional 10 min, cool it to room
temperature, and further cool the tube thoroughly in icy water for 2 min. Carefully add to the
solution 0.5 mL of icy water dropwise with thorough mixing with a stainless steel spatula,
followed by the dropwise addition of 3 M aqueous sodium hydroxide solution (3 mL).
(CAUTION: Concentrated sodium hydroxide solution is very corrosive. Avoid getting it onto
your hand. If your fingers feel kind of slippery, that means NaOH is starting to dissolve part of
your skin. Make sure to wash your affected skin area immediately if there is any exposure to
NaOH.) Mix the contents even with the spatula. Put a filter paper on the Hirsh funnel and wet it
with 2 drops of water. Using as much water as needed, transfer all solid in the tube onto the filter
paper and perform vacuum filtration. Wash the solid thoroughly with water twice (2 mL x 2) and
ethanol once (5 drops). Each time when a washing solvent is added, the vacuum line should be
detached, and the solid should be mixed well with the liquid using a spatula for ~0.5 min before
vacuum is applied. After the ethanol wash connect the filter flask to medium to strong vacuum
for 3 min until you get a solid which appears loose and dry. The liquid filtrate can be washed
down the sink with plenty of water.
Dissolve the dry crude product in a 10-mL Erlenmeyer flask in 1 mL of hexane. Heat it
briefly in the previous 95 oC water bath while swirling the flask. If the solvent begins to boil take
out the flask immediately. If you use pipette for transferring the solvent make sure it is clean and
dry. The solution for recrystallization should be free of any visible water. If a transparent
yellow/orange solution still cannot be made, add more hexanes dropwise, heat the mixture up for
a few seconds, and shake the mixture until there is little visible solid left. If after ~ 2 mL of
hexane has been used but you still see a small amount of water droplets or insoluble black
materials at the bottom, quickly transfer all the top clear solution into another dry clean flask
with a dry clean pipette while leaving the water and black impurities behind. Allow the
transparent solution to cool slowly to room temperature and further cool it in an ice bath for 5
min. (Note: a small beaker with mainly ice and little water should be used. Make sure that no
water gets in the Erlenmeyer flask.) Note the shape and color of any crystal that is formed. Put a
filter paper on the Hirsh funnel and wet it with 2 drops of water. Agitate the mixture in the
Erlenmeyer flask with a spatula and pour it out onto the filter paper and perform vacuum
filtration. Use small batches of cold hexanes (cooled in ice bath, total volume < 2 mL) to rinse
out the residual solid in the flask. Connect the filter flask to medium to strong vacuum for 5 min
until you get a solid which appears loose and dry. (You should be able to hear the hissing of air
passing through the filter. Make sure there are no significant amount of liquid in the filter flask
and that no liquid gets into the rubber tube connecting the filter flask to the vacuum outlet.)
Determine the weight of your product for later yield calculation.
Submit your sample to Dr. Wang for IR analysis. Dispose of the organic filtrate in
organic solvent wastes and your product in solid wastes. Dump all other liquids down the sink,
and wash all your glassware clean with soap water and finally rinse with a small amount of
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