Download Lab Reports File

College of Engineering,
Science and Technology
School of Sciences
Natabua Campus PO Box 5529
Lautoka (FIJI)
CHM 703 Laboratory
Lab Reports
Unlike your notebook, a report is intended for someone else's eyes. It should present the background
of the experiment, state the experimental procedure in a manner that allows it to be reproduced, and
discuss and summarize the results, all preferably in a format familiar to every professional working
in the discipline. The format of the report will be approximately, that of a research paper in a
chemistry journal. Every report will therefore be an exercise in scientific writing.
Scientific writing should be clear and organized. Say exactly what you mean as simply and
accurately as you can. Be brief. Don't be verbose or stilted. However, do get used to the scientific
terms commonly used to describe certain operations, e.g., refluxed, filtered, recrystallized, distilled,
etc. Learn the jargon and be consistent in the use of units, names, abbreviations, tense, etc.. This will
actually shorten your report and make it easier to write.
The total length of each report should not exceed about 4 pages, including the title page. In general,
and always when describing the experimental procedure, use the Third Person, the Passive Voice
and the Past Tense (e.g., "sodium acetate was added to the reaction mixture," not "I added sodium
acetate to the reaction mixture," or "add sodium acetate to the reaction mixture.”) Although this is
not a class on writing skills, I expect all reports to be written in good, grammatical English.
Handwritten reports are acceptable as long as your handwriting is legible. However, I strongly
recommend using a word processor. Note: do not write the lab report in your lab notebook.
1.
2.
3.
4.
Your report should be written in a format that consists of the following sections:
Title page
Introduction / statement of objectives.
Experimental procedure / results.
Discussion.
1
Title Page
This page should have on it the title of the experiment, the date(s) on which it was done, and your
name, FNU ID number, and College.
Introduction
This should begin on a new page, and should include a statement of your objectives (i.e., the
purpose of your experiment), an outline of the theory involved, including chemical equations for any
reactions, and possibly a brief discussion of why the technique is interesting or important. The
whole thing should occupy no more than half a page. Don't give a detailed experimental
procedure under the guise of an introduction. This is a very common error, for which no
credit will be given.
Experimental Section
This should consist of a very concise description of what you actually did. Remember to use the
Third Person, the Passive Voice and the Past Tense. DO NOT RE-WRITE THE PROCEDURE
GIVEN IN A LAB HANDOUT OR A TEXTBOOK. Where relevant, include numerical data (how
much starting materials, solvent, etc. you used, weights, volumes, spectroscopic data if any, etc.). Be
sure to include your final experimental results, showing your calculations, and expressing numerical
results to the correct number of significant figures, based on your estimate of the experimental
uncertainty. All this information should be presented in such a way that another person can repeat
the experiment in virtually the same way.
Results and Discussion
Very little numerical calculation is required in most organic chemistry experiments. However, every
synthesis experiment must include a percentage yield, usually expressed to two, at most three,
significant figures (i.e., at most one decimal place, but usually none). This is calculated using the
formula
number of moles of product
percentage yield = number of moles of limiting starting material x 100.
For the experiments you will be doing in this course, very little discussion will be needed, especially
if all goes as planned. If you data needs to be interpreted, this is the place to do it. If a problem arises
(a poor yield, a yield in excess of 100% (!), a synthesis that failed to work) attempt to explain it
here. If you can think of a better way to do the experiment, make your suggestions here.
2
Sample Lab Report
Synthesis of 2-Chloro-2-methylbutane from 2-Methyl-2-butanol
Introduction
2-Methyl-2-butanol, also known as tert-amyl alcohol, is a tertiary
alcohol that undergoes a facile reaction with conc.HCl to give the
corresponding
alkyl
halide,
2-chloro-2-methylbutane,
via
a
mechanism that involves the formation of a stable tertiary
carbocation. The reaction is much less easy with primary and
secondary alcohols.
The objective of this experiment was to synthesize the product, and
to study the techniques of extraction and distillation used to
purify it.
Experimental Procedure
2-Methyl-2-butanol (27 mL, 0.25 mol) and conc. HCl (65 mL) were
shaken together in a 125 mL separatory funnel for several minutes,
then allowed to stand for 15 minutes, during which time 2 layers
separated. The lower (aqueous) layer was drained off, and the upper
layer (product) was washed with 20 mL of 5% NaHCO3 solution (to
remove excess acid) and with 20 mL of water. It was then dried with
anhydrous CaCl2 and purified by simple distillation (b.p. 85°C).
The yield was 17.2 g (65%).
Discussion
The procedure was operationally very straightforward. Since the
reaction is reversible, a better yield could perhaps be obtained by
using gaseous HCl rather than the aqueous acid, but this may entail
special techniques.
3