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. General guidelines for writing reports

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:

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.

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