Formal report for the Atomic Absorption Lab



The report should be 3 (minimum) to 5 (maximum) double-spaced pages (including graphs and figures) using 12 pt Times New Roman font on 8.5 x 11 inch paper with 1 inch margins.  If graphs and figures are included, they should not take up more than a total of one page in all.  Cover pages, which are not required, do not count toward the page total.  The report will be worth 10 laboratory points.  The report is due at the beginning of lecture on April 30.



The purpose of the formal report is to describe the analysis of your tap water sample.  You could think of it as a report to a client that has hired you to analyze their water for Ca2+ and Mg2+.  There normally is a fair amount of freedom in how such technical reports are organized.  However, to make it easier for us to compare different reports, we request the report to have the following parts:

     1. Introduction.  You should indicate the purpose of the study and include a brief discussion of what affects Ca2+ and Mg2+ concentrations in the tap water of Sacramento and its surroundings.  You can also use information from the class website and other sources to discuss water quality.

     2. Experimental Methods.  This should include a brief general description of how the atomic absorption spectrometer (AAS) works and the methods you used to analyze the samples.  It is important that the description of the instrument and how it works is accurate.  When writing a description of the methods, the focus should be on the main steps that you took.  This should include how standards were prepared, how the tap water sample was diluted, and how samples were analyzed.  It is not helpful to restate the procedure in the lab syllabus.  For example, writing "we calculated the dilution factor necessary to produce four Mg2+ standards into the 0-1.0 ppm range" does not tell the reader what dilution was used or, more importantly, the actual Mg2+ standard concentrations or range of Mg2+ standard concentrations.  This section does not need to be highly detailed.  For example, a detailed list of operational parameters of the AAS, including slit widths and flow setting, and the specific glassware used to make your dilutions is not needed.  Statements such as, “The calcium hollow cathode lamp was turned on by choosing the lamps menu and selecting the ‘Ca2+, Mg2+’ lamp from the list” are not appropriate.  It is too detailed, and too specific to the particular AAS that you used.  A more appropriate statement would be, “A hollow cathode lamp containing the element calcium was utilized as a light source at 422.7 nm for the detection of calcium ion in water samples.”  Avoid the nitty-gritty details, and stick to the general theory and process.  Based on your description, another chemist familiar with AA should be able to replicate your experiment.

     3. Results/Discussion.  This section should include the tap water Ca2+ and Mg2+ concentrations, a discussion of the quality of the results, and a discussion of what the concentrations mean in the context of other measurements.  To indicate the quality of the measurements, you may want to discuss the calibration curves that you produced, the uncertainty in the tap water concentrations and the error in the unknown measurement (this should be available when the AA (informal) lab report is returned).  A discussion of the meaning of the tap water concentrations normally will also include a comparison to measurements from other samples collected in the vicinity, if possible, and/or from other samples of similar concentration.  Data from the entire class in addition to several past classes will be available on the web-site as soon as it can be compiled.  Compare your tap-water with other samples from your own area if possible, and from other areas as well.  Use the statistical methods that we have discussed in lecture and are outlined in the textbook.  If you use tables or figures in your discussion, be sure to first describe these in the text, and then fully explain them.  Never place tables or figures into a paper or report that are not fully interpreted in the text.  Tables and figures should only display final data; it is not appropriate to present raw data and expect readers to analyze it themselves.  Be sure that all reported values have the correct units and significant figures.  This is true for all sections of the report.

Important Caution:  If you take specific information from sources (as mentioned above), they should be referenced.  You should write descriptions in your own words.  Copying whole sentences or phrases from other sources without putting them in quotations is considered plagiarism (a form of cheating by stealing someone else's writing).  However, in scientific writing it is extremely uncommon to directly quote others' work unless it is absolutely impossible to covey the same information in your own words.  You are welcome (in fact recommended) to work with others provided you are doing the writing yourself.  A positive way to work with another is to exchange completed reports and proof-read each other's reports.  Students found to have parts of the report written identically to others may be considered to have plagiarized their reports.



About half of your grade for this report will be based on the clarity and grammar.  This means that the reader should be able to follow and understand what you are trying to say.  Also, it should be said in a grammatically correct way.  This means proper spelling, punctuation, and sentence structure.  It is recommended that you and a classmate exchange reports to proofread.  The rest of the grade will be based on the completeness and general content of the report (inclusion of parts listed above).  Please read the 'General Guide to Writing Formal Lab Reports' that is provided through the course webpage and follow the advice given in that document.