WRAD: Writing Guide for Chemistry

WRAD: Writing Guide for Chemistry

Table of Contents

Resources for help with writing

General guidelines for writing reports

Presenting data... the good, the bad, and the ugly

Standard formats

Writing ethics

Some real examples

Resources for help with writing

1. It may seem obvious, but remember that your instructors are there to help. Did they provide handouts or online information with specific instructions on style, format, and a checklist of items to include in the report? Since expectations will vary from class to class, and sometimes even from report to report, it is important to understand what is being requested before organizing your results and beginning to write. A grading sheet specifying the number of points or relative weight given to each part of the report can help you to focus your efforts. Find out if your instructor will provide these in advance.

2. The ACS Style Guide, A Manual for Authors and Editors, 2^nd ed. (Dodd, J., Ed.; American Chemical Society, Washington, DC, 1997) is an excellent resource with writing tips and detailed descriptions of the ACS writing conventions. The guide can be ordered at http://www.oup-usa.org/j778/isbn/0841234620.html.

3. Some handy online resources:

100 + online writing labs (short instructional pages)		http://owl.english.purdue.edu/handouts/index.html
Links about scientific and technical writing		http://www.inkspot.com/genres/tech/
General guide to grammar and writing		http://webster.commnet.edu/grammar/index.htm
An online course in science and technological writing		http://members.home.net/tgeorges/write
Guide to writing a thesis or dissertation		http://www.learnerassociates.net/dissthes/
Links from the OSU writing center		http://osu.orst.edu/dept/writing-center/resources.html
Handling electronic references	http://www.chem.orst.edu/electronic_references.htm

General guidelines for writing reports

As noted above, instructors differ in their expectations for lab reports. This is reasonable when you consider that there is also a wide variation in the requirements for different chemistry journals and publishers. Even so, a long experience in reading lab reports, papers, and thesis drafts indicates that there are common areas of confusion for many students, and therefore we provide a few general guidelines to help in creating reports or publications.

1. Use the correct verb tense

Lab reports and research papers should be mainly written in the present tense. You should limit the use of the past tense to (1) describing specific experimental methods and observations, and (2) citing results published in the past. The following sentences can be written in the past tense:

The solid was washed with water, then dried overnight in a dessicator.

Jones et al found that polymers with absorption maxima between 200 and 300 nm degraded when exposed to ultraviolet radiation.[1]

Data analyses, on the other hand, should be written in the present tense:

Extrapolation of the line in Figure 3a gives a polymer viscosity of 40.2 cp: an error estimate using eq. 2 provides an uncertainty of 0.4 cp.

2. Write in the third person

A common question is whether the words I, me, my, we, our, or us, belong in science writing. Because scientific experiments demonstrate facts that do not depend on the observer, reports should avoid using the first and second person. For example, the second sentence below is better because it avoids the use of the first person:

I stirred the solution for 2 h; then I obtained a yellow powder by filtration.

Stirring the solution for 2 h, and subsequent filtration, yielded a yellow powder.

However, when referring to your own results or conclusions, it can be simpler and clearer to use the first or second person:

While Smith and Jones report a cell dimension, c, of 23.3(1) Å, the authors’ own data indicate a value of 23.6(1) Å.

Smith and Jones report a cell dimension, c, of 23.2(1) Å, but our data yield a value of 23.6(1) Å.

The “authors’ own data” is an awkward phrase and “our data” in the latter sentence is better.

3. Be clear but concise

Reports and papers should fully describe experiments in a precise and factual manner. Both the depth of the error analysis and the writing style must be appropriate to this task. Consider the following sentence in a discussion:

The calorimeter vibrated a little, but it is still easy to measure the peak in Figure 1 very accurately.

Words and phrases such as “a little”, “easy”, and “very accurately” have no definite meaning, and are therefore inadequate. Quantitative, or semi-quantitative, descriptions and analyses are always preferred over the use of such imprecise terms. In the following rewrite, the error is much more clearly described:

The largest source of error is vibration, which is estimated at 1–5 W/kg RMS. This adds at most a 4% uncertainty to the peak integration, and values obtained are therefore reported as +- 4%.

Although you should strive to describe experiments in sufficient detail to be reproduced, it is also important to write concisely. Often, text can shortened by condensing or rephrasing without decreasing the meaningful content. In the two examples below, the latter conveys the same information in a more concise, and preferred, writing style.

Distillation fractions three and four were combined in a 100ml round-bottom flask. To this flask was added 1.966g (0.0114 mol) of benzoic acid. The flask was then connected to a long column, distilling head, and condenser. Glass-wool and foil was again wrapped around the column and distilling head.

In a 100 mL round bottom flask equipped with a water jacketed condenser and wrapped column and head, 1.966 g (0.0114 mol) of benzoic acid was added to the combined third and fourth fractions.

4. Revise and proofread

Treat your first written copy as a draft, and then read through and revise. In WIC courses, some assignments will have revision steps included in the submission and grading process. Many students are surprised at how many simple errors can be found in first drafts, and how much their writing improves after using this simple method. A final proofreading is also important, and can help to minimize spelling and typographical errors. A few minor errors are almost inevitable in any written document, but reviewers, and instructors, can usually tell when they are reading a first draft. Along with a “human” proofread, use a spell check routine to help spot errors.

Presenting data...the good, the bad, and the ugly

Reports should usually include a narrative text that describes and explains the information presented. Use the results section to explain the purpose of every figure, schemes, equation and table. Published research results never include “orphan” data, that is, information that is not explained or put into context by the written text. This is also a good rule to follow in lab reports.

When referring to a figure, table, or equation, use its number in the text, for example:

A plateau was observed at reduced pressures greater than 0.1, as indicated in Table 1.

It follows that every figure, table and equation needs a number. Figures and tables require a caption that includes the number and a descriptive title:

Figure 1. Mass uptake vs. reduced pressure for Zeolite 5A.

Table 1. Powder Diffraction Data Obtained for Zeolite 5A.

Note that the labels “chart” and “graph” are somewhat antiquated terms, and have been largely replaced by “figure”. Equations will normally have a number placed in parentheses at the right margin:

E = mc² (1)

Here are some additional tips for preparing figures and tables:

Ø All graph axes require labels that include both the variable name and units.

Ø Axes should use reasonable scales to clearly show the data and have labeled tic marks. The axis labels do not need to show the full number of significant figures.

Ø Table columns should specify the units employed under each heading.

Standard formats

Instructors (and editors) can be picky about writing conventions. Literature citations, symbols, and abbreviations all require strict adherence to a standard format. Unfortunately, the particular standard used varies between publishers. An important standard is that adopted by the American Chemical Society (ACS), and this will be used by many chemistry lab courses at OSU. It would be quite difficult to memorize all the forms for literature citations alone. Fortunately, there is no need to do so. The ACS Style Guide (see above) lists all the required formats and provides easily-followed examples. Nevertheless, it’s useful to be familiar with the most common citation formats and abbreviations. Some frequently-used ACS formats are provided below.

For journal articles:

1. Bode, H.; Jenssen, H.; Bandte, F. Angew. Chem. 1953, 65, 30.

Note – “65” is in italics and refers to the volume number, and “30” is the first page of the article.

For books:

2. Dresselhaus, M.; Dresselhaus, G.; Eklund, P. Science of Fullerenes and Carbon Nanotubes; Academic: New York, 1996; pp 126-141.

3. Watanabe, N.; Touahra, H.; Bartlett, N.; Mallouk, T. Fluorine Intercalation Compounds of Graphite. In Inorganic Solid Fluorides: Chemistry and Physics; Hagenmuller, P., Ed.; Academic Press: New York, 1985; pp 331-369.

For websites:

4. Oregon State University Chem 462 Lecture Notes. http://www.chem.orst.edu/ch411/ch411cn.htm (accessed May, 2000).

Writing Ethics

In the sciences, results are usually discussed in relation to the work of others. Your writing will therefore often refer to results or conclusions that are not your own. This is fine as long as you clearly distinguish between your results and those obtained from other workers or the literature. Each time outside results are cited, a reference must be provided to the original source.

A related issue lies in the use of quotes from another work. The exact duplication of text from an outside source is acceptable only if it is placed in quotations and a reference provided. Paraphrasing or summarizing other results can also be acceptable if a reference is provided. However, incorporating another author’s words or style into your own writing is not allowed, even if the original work is referenced.

When there are group assignments or reports, make certain that you understand the instructor’s expectations for shared vs. individual contributions. Students often do experimental work in groups, and are encouraged to discuss the lab results and data analyses with others. However, report writing is most often expected to be an individual effort.

Some real examples

The following are all examples taken from student reports in OSU chemistry. In each case, a revised version follows the original text. For practice, read each original text, then compose a revised version before reading the one provided.

1.	Original text:	Distillation fractions three and four were combined in a 100ml round-bottom flask. To this flask was added 1.966g (0.0114 mol) of benzoic acid. The flask was then connected to a long column, distilling head, and condenser. Glass-wool and foil was again wrapped around the column and distilling head.
	Revised form:	In a 100 ml round bottom flask equipped with a water jacketed condenser and wrapped column and head, 1.966 g (0.0114 mol) of benzoic acid were added to the combined third and fourth fractions.

Original text:

Next the copper solution was prepared. This was done by weighing out 0.1821 g of copper nitrate and diluting it in 10mL of tap water.

Revised form:

A solution was prepared by dissolving copper nitrate (0.1821 g) in tap water (10 mL).

Original text:

If for example, we could have used a red and green apple to determine the components, we could have averaged the data and obtained more accurate results.

Revised form:

If, for example, data were obtained from both a red and a green apple, the averaged results could provide more representative values.

Original text:

This experiment intends to investigate upon any measurable amounts of Nickel in the surrounding mud area and within barnacles living on the pilings.

Revised form:

The purpose of this experiment is to determine the nickel content in the surrounding mud area and in the barnacles living on the pilings.

Original text:

For the final yield of pentene isomers, only the elimination sample was considered…The yields are reported in Table 2-3.

Revised form:

The calculated final yields of pentene isomers (Tables 2 and 3) are based on the elimination step only.

Original text:

The contents of the flask were poured into a separatory funnel, and mixed with increasing vigor. The evolving gas was vented periodically. The product was allowed to separate into two distinct layers. The bottom, aqueous, layer was bright yellow. The top, ether, layer was reddish-brown and transparent. Each layer was decanted into separate containers.

Revised form:

The product was transferred to a 1 L separatory funnel and upon mixing separated into a bright yellow solution (bottom layer) and a clear ethereal reddish-brown layer with the evolution of carbon dioxide.

Original text:

The final solution was cooled using an acetone-ice bath. A temperature of -5 C was necessary to avoid the decomposition of the diazonium salt. Hypophosphorous acid and sodium nitrite were slowly added.

Revised form:

To avoid the decomposition of the diazonium salt, the resulting solution was cooled to -5 °C using an acetone-ice bath and then hypophosphorous acid and sodium nitrite slowly added.

Original text:

Revised form:

Original text:

The first part of this experiment was to determine the percent removal of lead, calcium, magnesium, and copper. We had thought that there was not enough lead and copper left after we filtered the tap water, so two spiked solutions were made.

Revised form:

The purpose of the first part of this experiment is to determine how effectively filtration removes lead, calcium, magnesium, and copper from tap water. Although low levels of the metals were accurately detected in spiked solutions, no detectable Pb or Cu was found in the filtered sample.

10.

Original text:

This should have given us a 5.00ppm solution instead the ICP data showed that we had a 1.373(+/-0.0374)ppm. We decided that we would use the ICP data for all our calculations.

Revised form:

ICP data indicated that the solution prepared to contain a Pb concentration of 5.00 ppm actually contained 1.373 +/- 0.037 ppm. The ICP values were used in subsequent calculations.

11.

Original text:

The standard addition for the tonic water was done by using the tonic water solution and doing a 1 to 10mL dilution on it with the sulfuric acid. A signal was obtained for the sample. After the first signal was taken 15μL of 10ppm quinine sulfate stock was added, the signal was then taken.

Revised form:

For the standard addition measurement on tonic water, first a tonic water test solution was diluted 1 to 10 with sulfuric acid in a 10 mL volumetric. The absorbance was measured before and after 15 μL of a 10 ppm quinine sulfate stock solution was added to the cuvette.

12.

Original text:

It was observed that the barnacle sample was very well digested, but minute traces of sludge were still found in the mud cell. Indications of this left over sludge may be from silicon waste left in the sand and could not be further digested with the acid used. This silicon waste was found to be negligible due to the belief that all of the existing Nickel on the silicon was dissolved by the HNO₃.

Revised form:

The barnacle sample was very well digested, but minute traces of particulates remained in the mud cell. These particulates are assumed to be silica from sand since all other known components dissolve in nitric acid.

13.

Original text:

The following standard concentrations were used to follow Beer’s law for the absorbances at the corresponding wavelength: (Table)

Revised form:

The standard concentrations were measured at the corresponding wavelengths and the data provided in Table 1.

14.

Original text:

Some changes were made to this procedure with one of them being that the absorption corresponding to the galactose was not found for both sample sets. ...Another change is that the final absorption readings were taken 20 minutes after adding the final enzyme, β-galatose dehydrogenase, instead of 15 minutes.

Revised form:

One change made to the written procedure was that the absorbance due to galactose was not obtained for both sample sets. ..... A second change was that the final absorbance measurement was made at 20 min instead of the suggested 15 min after adding β-galatose dehydrogenase.

15.

Original text:

Twelve penny solutions were analyzed using flame atomic absorption, and this data was used to construct a calibration curve for each metal.

Revised form:

The twelve solutions obtained by dissolving pennies were analyzed using flame atomic absorption spectrophotometry, and these data were used to construct a calibration curve for each metal.

Credits:

Oregon State University Chemistry Dept.