Guidelines for writing AP Chem laboratory reports

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Guidelines for writing a formal laboratory report.
Scientific breakthroughs (even in the AP lab) are pretty useless if they are not communicated. A brief search of the web reveals
hundreds of sites showing how to write a laboratory report -- all following essentially the same format so as to make it easier
for scientists to read each other’s reports.
A few tips before you start your experiment:
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Understand the goal of the lab. What are you are trying to determine or support?
Be clear about the variables you are measuring and the equations that connect them.
Are your measurements repeatable?
— You should be able to get the same results tomorrow as today.
Before you break down the equipment do a quick check. Do your results make sense?
Make sure you have enough data. It is ok to make more measurements than suggested in the instructions.
Be curious – inquiring minds want to know.
Be observant – chance favors the prepared mind.
Formal Laboratory Reports
The first page needs the following identifying information:
Title of experiment
Your name
Your lab partner’s name(s) (in parentheses)
Your teacher’s name
The due date
The class
This may be a separate cover page, but it wastes less paper if this information is given at the top of the first page of the body of
the report. All formal reports will be typed, printed out and handed in on due date.
(Use these section headings with the Roman numerals. You are telling a story but not writing a novel)
I. INTRODUCTION (what is the question (hypothesis), why is it interesting and maybe what has been done before)
The introduction acquaints the reader with the topic in general and your problem or questions in particular. Write this as if you
were explaining concepts to a ninth grader or your dog—your choice. Why is this question important? (From a scientific and
historical standpoint) What is the goal of the experiment? For labs where you are trying to support a hypothesis, formulate and
state your question in the form of a hypothesis at the end of the introduction. If you are trying to measure something, just state
the quantity you are trying to measure.
II. PROCEDURE (what you actually did in the lab)
If you developed the procedure, which we will do several times in this class you should give a detailed description of the
methods used to obtain the data and the equipment used. When a full procedure section is required, write it from the
perspective of what has been performed, not what you will do. Do not write step-by-step instructions. Tell the reader in easy to
understand sentences what in general was done. Assume the reader has some basic laboratory skills.
If the procedure has been given to you, there is no need to repeat all the details in the report. A brief description of the methods
and equipment used to perform the experiment is sufficient. You should, however, report any alterations to the given
procedure.
If you use an uncommon piece of lab equipment or specialized lab equipment, the make and model number of the equipment
should be reported the first time it is mentioned.
III.
DATA (the numbers you actually get in the lab)
This section includes numerical data and any observations made during the experiment. Numerical data should be in tables,
either neatly drawn with a ruler or generated by a word processor. Correct significant figures should be used on all numbers.
Units should be included with column headings giving quantities measured. Use separate data tables when measuring a
different variable.
Trial
1
2
3
Average
IV.
Mass (kg)
27.50
27.49
27.35
Speed (m/s)
17.124
17.122
17.132
Force (N)
2.1
2.2
2.0
Time (s)
.113
.115
.110
ANALYSIS (any math you do on the data you collected and any graphs you make)
This section includes any calculations required. If you are required to make a repetitive calculation with your data you should
include a sample calculation. You can handwrite (neatly) any calculations.
If graphs are used please see the attached sheet for correct graph formatting. A line of best fit should be included on the graph.
This can be done by hand or through statistical methods if desired. In this section you should help the reader interpret the
graph. You are not giving a visual description of the graph, i.e. “The graph shows a line going up”. We are assuming some
intelligence on the part of the readers. Your job is to make an explicit connection between independent and dependent
variables, “The graph shows that when we increase the temperature, the volume of the balloon increases (linearly)
(exponentially).” Any conclusions about what this may mean or why it happens this way are saved for the final section.
V.
RESULTS
(this is what you observed/measured/found as a result of lab measurements)
What you say depends on type of lab, are you finding a value for a known constant or testing a hypothesis?
This is where you report the results of your analysis and observations.
Examples: Not all of these will be used in every lab
 “We found the value of the magnetic moment to be …….”,
 “We found that as we increased x that y decreased exponentially.
 “We found the value of the density of non-existium to be 250.67 g/mL” The accepted value is 245.326 g/mL (cite source
for this value)” Calculate % error
 “The graphed data shows that as the mass of the monster increases, the total area of Tokyo destroyed increases”
 “In this lab we found that that as temperature increased, the volume of the balloon increased.” (testing a hypothesis)
 “Human error” is never a reason for unexpected results
VI. CONCLUSIONS
(This is what your results mean in a larger context. Here you interpret your results for your audience)
Here is where you bring your tale to a close. You discuss what you have learned by conducting this research. Whether your
hypothesis was supported or disproved. In this section you can compare your results to established values. If your values differ
from previously published values (cite sources!) you should discuss why you think this is so. Part of this section includes a
discussion of sources of error (uncertainty) in the experiment and just as importantly, how they affect the final results. “We
think the scale measured the mass as 0.10 grams larger than it should have and therefore our density is larger than if the scale
had been accurate.” You should also discuss any limitations on collecting the data which naturally leads to suggestions for
improvements to the experiment.
Examples Not all of these will be used in every lab
 Discuss the extent to which your data supported your hypothesis. If not, explain why not.
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If you know you made a mistake in the lab discuss the effect of the mistake on your result. It is not enough to say we
measured something wrong and we got the wrong answer. “The measured value of x was lower than it should have been
because …. As a result this increased/decreased the calculated value of y”
Explain why your value didn’t match the accepted value (once again “Human Error” is not an acceptable explanation).
You must describe specific conditions in the lab that led to the discrepancy and how they affected the results obtained.
These are called sources of error in the lab (uncertainty). This not error in the sense of mistakes—you already discussed
your mistakes above. “It was difficult to measure x because…. This resulted in a higher/lower value of y”
The above leads naturally to a discussion of how to improve. Better equipment is not a useful answer here. It is an obvious
solution but not helpful. How could you have improved your technique on the lab using the existing equipment?
VII. REFERENCES
(Include in this section bibliographic information on anything referenced in the above sections. How to cite a web
document is at the very end)
Citations: Any information you look up that you include in your report needs to be properly cited.
AIP Style Manual References
The American Institute of Physics (AIP) has a Style Manual (4th Edition, 1990) which specifies how to format text for
submission to an AIP journal (such as Physics Today or Physical Review). A style manual for Physical Review is available
online at
http://publish.aps.org/STYLE/index.html
Below is a summary of how to quote sources using the AIP format.
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A reference to a source or other supplementary information is given by a superscript (such as 1,2,3).
References are numbered by order of appearance in the text.
All of the references/supplementary information is included at the end of the document.
Authors are indicated by their initials followed by their last name.
If a paper has more than 4 authors, quote only the first author's name followed by et al.
Never include a reference number adjacent to an equation or symbol. This can lead to confusion that the number
indicates a power rather than a reference.
Abbreviate the title of journals and eliminate words like "of" or "the." Some of the more common abbreviations are:
American (Am.), Journal (J.), Letters (Lett.), Physics (Phys.), Review (Rev.), Scientific or Science (Sci.). This means
"American Journal of Physics" would be abbreviated "Am. J. Phys." and "Physical Review Letters" would be
abbreviated "Phys. Rev. Lett."
A sample section of a paper, including references that would appear at the end of the paper, is shown below:
The first experimental search of muonium-antimuonium conversion, in 1968, placed a 95% confidence upper limit1 of
G<5800GF on the four-fermion coupling constant.2 A number of experiments 3,4 have placed more stringent limits on
this conversion. The first run of the current TRIUMF experiment published the limit5 G<0.88GF (90% confidence). A
preliminary upper limit of G<0.5GF has been quoted by a LAMPF experiment.6 Using a longer run than our previous
result,5 we report the final results of the TRIUMF experiment of G<0.29GF (90% confidence) on the conversion
of muonium to antimuonium.
1
J.J. Amato et al., Phys. Rev. Lett. 21, 1709 (1968).
GF is the Fermi coupling constant 1.16637(2)×10-5 GeV-2(hbar c)3, from Review of Particle Properties, Phys. Lett. B 204, 51
(1988).
3
W.C. Barber et al., Phys. Rev. Lett. 22, 902 (1969); G.M. Marshall et al., Phys. Rev. D 25, 1174 (1982); B. Ni et al., Phys.
Rev. Lett. 59, 2716 (1987); Nucl. Phys. A478, 757c (1988).
4
G.A. Beer et al., Phys. Rev. Lett. 57, 671 (1986).
5
T.M. Huber et al., Phys. Rev. Lett. 61, 2189 (1988).
6
H.J. Mundinger et al., in Rare Decay Symposium, edited by D. Bryman, J. Ng, T. Numao, and J.-M. Poutissou (World
Scientific, Singapore, 1989).
2
[The text above is a slightly modified excerpt from Search for Mixing of Muonium and Antimuonium, T.M. Huber et al., Phys.
Rev. D 41, 2709 (1990). ]
A couple of comments on how references were included in this paper.
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For reference 1, notice that the 1 is placed in the text
... upper limit1 of G<5800GF on the ...
instead of
... upper limit of G<5800GF1 on the ...
which could lead to confusion that it implies GF to the 1st power.
The physical constant GF is quoted from a standard reference (with full errors). Always use a standard reference such
as the Reviews of Particle Properties or Physics Today (Part II, August of each year).
For a group of related sources, you can group them as in reference 3. You can also indicate multiple sources as in 3,4 (in
this paper, I needed to refer to the source in reference 4 later in the paper).
References 2 and 6 have been placed after the period in a sentence.
Notice that in the last sentence, the source 5 was referred to again - it is not necessary to make a new number to refer to
the same source.
Reference 6 shows an excerpt from a collection of articles in a book.
Examples of sources that you might reference
Below are some of the more important types of references that you may need in your reports.
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Reference to Article in a Journal: Indicate the Author(s) name, Journal Name (using abbreviations) Volume Number
(in Boldface), Starting page number, (year). Examples are shown in Ref. 1 and Refs. 3-5 above. For some journals
(such as Physics Today and Scientific American), you need to specify the issue number since they start at page 1 each
issue. For example, for an article which starts on page 25 of the November 1995 (Issue number 11) Physics Today, use
H.H. Seliger, Phys. Today 48 (11), 25 (1995).
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Reference to Material in a Book: To refer to material in a book (in this case, pages 100-102 from Serway), the
reference would be similar to:
1
R.A. Serway and J.W. Jewett, Physics for Scientists and Engineers, 6th Ed. (Thomson, Belmont, CA, 2004),
pp. 100-102.
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Reference to Article in a Book: See the example in Ref. 6 above.
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Reference to a Computer Program:
1
T. Huber and S. Mellema, Computer Program Modelfit, (Gustavus Adolphus College, Unpublished).
Computer Program SIGMAPLOT Version 5.0, (Jandel Scientific, 1992).
2
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Reference to a WWW Document: The AIP style manual has no format listed for this (the WWW did not exist in
1990 when the AIP style manual was published!). The essential thing is to include the full URL address of the source
(otherwise it is impossible to find the document). For lack of an "official" style, use a format which is similar to:
1
T.M. Huber, How To Locate Material for Formal Reports, WWW Document,
(http://physics.gac.edu/~huber/misc/finding.htm).
Electronic Copy: http://physics.gac.edu/~huber/misc/aiprefs.htm
Revised: 15-Mar-2006 by Tom Huber, Physics Department, Gustavus Adolphus College.
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