Exp. 2: Spectroscopy I
Dec 21, 2012
Partner: Christmas Jones
Comment [WO1]: All information listed on page
4 is included. This section does not need to be double spaced.
Page numbers added in case your staple comes loose and pages get scattered.
The objective of the experiment was to determine the unknown concentration of a chromophore, Sample XYZ (XYZ), in an aqueous solution by applying the Beer-Lambert equation. In order to complete this objective, the wavelength of maximum absorbance (λmax) of XYZ and the molar
Comment [WO2]: Complete sentences are used to describe the goal of the experiment.
Comment [WO3]: If you are going to use an abbreviation in the report, it should be written out in full the first time and defined in parentheses.
absorptivity of XYZ at λmax (εmax) were first determined.
Comment [WO4]: The secondary objectives are listed along with the overall objective.
Comment [WO5]: The procedure is written in past tense, as the experiment has already been performed. Also, there is no use of the first person
“I, we” or “one must/the student must”.
The procedure used was based on that in Semi-Quantitative Experiments for General Chemistry,
Complete sentences are used, and it is written in paragraph form.
The University of Akron, Summer 2011 Edition (course lab manual). Two matching cuvettes were
All text is DOUBLE SPACED
obtained by following the procedure on pages 9-10 of the lab manual. Once the standard and reference cuvettes were established, the λmax value of XYZ was determined. The sample cuvette was filled with
There are no words such as “first, then, next, last”, etc. It is assumed that the events took place in the order they were written, unless stated otherwise.
approximately three mL of the Sample XYZ standard solution, and the %T measurement was taken at the
A basic summary of the procedure is still given – even the parts that were done exactly as the manual said. starting wavelength of 510 nm, which was given on the reagent bottle. After taking %T measurements at
Comment [WO6]: The primary source that the procedure is taken from is cited.
500 nm and 520 nm, it was determined that measurements needed to be taken at increasing wavelengths. %T measurements were taken at 10 nm intervals, and then at 5 nm intervals, until a value for λmax was determined at the wavelength with the lowest corresponding %T value. For XYZ, the λmax value was determined to be 555 nm.
Having established the λmax of XYZ, the molar absorptivity at λmax (εmax) was determined. Burets were used to prepare four test tubes containing diluted XYZ in water. The volume of each solution added was based on Table 1 on page 51 of the lab manual. The exact volumes added can be found in
Table 2 in the report. The solution in each test tube was stirred thoroughly and placed in a cuvette, and its %T was measured at 555 nm. The %T values of the four samples and the %T value of the standard XYZ
Comment [WO7]: The figures and tables in the report are labeled in numerical order, so they can be referenced in other parts of the report, such as here in the procedure. They should be in bold.
from part A were converted into absorbance (A) values. These A values were plotted against the corresponding concentration of XYZ in each of the four test tubes and the standard solution, giving a
Beer-Lambert plot. The εmax value was derived from the line of best fit for the data, and was determined to be
Comment [WO8]: The procedure explains how the data was used.