Chemistry 122: Advanced Analytical ChemistryStephen M. Contakes

Westmont College, Fall 2017 Semester

Lecture & Lab Times: Section 1: Tuesdays, 8 – 11:50 AM in Whittier Science 204Section 2: Tuesdays, 1:15 – 5:30 PM in Whittier Science 204

Table of ContentsA. Instructor & Office hours InformationB. Course descriptionC. Instructional & student goals & objectivesD. Educational philosophy and teaching proceduresE. Textbooks & other materialsF. Method of GradingG. Course policiesH. Disclaimer I. Tentative course schedule

A. Instructor & office hours information: Instructor:Stephen M. ContakesOffice: Whittier Science 218Phone/Voicemail: (805) 565-7153Cell phone: (626) 676-5084Fax: (805) 815-7066E-mail: scontakes@westmont.edu

Office Hours: Mondays, Wednesdays, and Friday’s 9:30-10:30 AM, Thursdays 10 AM – noon, and by appointment.

B. Course Description (from the University Catalogue):CHM 122 Advanced Analytical Chemistry (2) Prerequisites: CHM 101 and CHM 121 or consent of instructor. One lecture and one four-hour laboratory per week. Emphasis on instrumental methods of analysis including spectrophotometry, voltammetry, and gas and liquid chromatography.

C. Instructional goals & objectives:Student Learning Outcomes (things we will attempt to achieve):

1. You will gain additional practical experience with the following instrumental methods of analysis: Spectrochemical methods of analysis: Uv-vis spectrophotometry, atomic absorption spectroscopy, FTIR spectrophotometry, fluorescence spectroscopy. Analytical separations:Gas chromatography, high performance liquid chromatography/gel permeation chromatography, column chromatography, GC-mass spectrometry.

2. You will gain practical experience with several numerical methods including the construction and analysis of calibration curves, multivariable regression, and spectral deconvolution.

3. You will gain experience with the synthesis of high molecular weight synthetic polymers and their analysis by gel-permeation chromatography.

4. You will gain experience in the synthesis of metal oxide nanoparticles 5. You will gain experience with the keeping of complete, accurate, & properly annotated

lab records.6. You will learn how to prepare clear, structured, and well-written scientific reports.7. You will have thought about how professional chemical practice can impact Christians’

moral and spiritual development.

Chemistry department program learning outcomes (how the student learning outcomes connect with what the Chemistry department expects of its majors):

1. Core Knowledge. Students will demonstrate a breadth and depth of knowledge in chemistry. This goal is advanced by student learning outcomes 1-4, which will provide you with practical experience in instrumental methods and data analysis techniques, macromolecular chemistry, and nanochemistry. The depth of your understanding of these techniques and their application will be primarily assessed through your lab reports and notebook entries. Specifically, you will be expected to understand each of these techniques and methods to the point where you are able to craft a skillful and appropriate introduction to each lab’s experimental strategy; describe the experiment itself in an organized and insightful way that outlines the key experimental parameters and give a reader a clear idea of what is important about each experiment; present, describe, evaluate, and summarize your results and their limitations in a professional and insightful manner using text appropriately and judiciously supplemented by clear and graphically appealing schemes, figures, and tables. Your technical mastery of how the equipment works will also be assessed orally at the bench in terms of how well you are able to describe each instrument’s operation and the function of various artifacts (sources, detectors, columns, etc…) taken from decommissioned instruments and spare parts reserves. This course will also develop your scientific writing skills beyond that expected in earlier courses.

2. Experimental Design. Students will be skilled in working in the laboratory and will be competent in experiment design and problem solving by the time of graduation. This goal will be advanced by student learning outcomes 1-6. In particular, the prelab lecture and discussion activities will provide you experience in evaluating the advantages and disadvantages of various analytical techniques for a given application and in selecting appropriate conditions for a given analysis. Your skills in this area will be reinforced and assessed at the course-concluding problem solving workshop.

3. Christian Connection. Our students will be experienced at reconciling Christian and scientific world views. They will have a perspective that integrates their scientific and theological beliefs into a seamless whole. Learning goal seven will focus on practical theology aspects of this integration. Specifically, you will be encouraged to view their attitudes toward laboratory work and behavior in the lab as an outward expression of your beliefs and to reflect on how you might better align your theological convictions and laboratory practices.

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Course Methodology (things we will do):1. You will gain practical experiences with common laboratory instrumentation and

techniques through a series of laboratory exercises.2. Textbook readings and pre-lab lectures will be used to give you an overview of the

instruments and techniques used in the various experiments and to prepare you to develop experimental protocols for addressing the lab exercises.

3. Lab notebook entries will be reviewed weekly for quality and completeness. 4. A short tutorial, reading, and set of guidelines will help prepare you to craft well-written

lab reports.5. Written laboratory reports will be used to assess your mastery of course objectives.6. A reading assignment and discussion will be used to explore how the practice of

chemical analysis can impact our Christian lives.

E. Textbooks and Other Materials:Required Textbook: Granger, Robert M.; Yochum, Hank M.; Granger, Jill N.; and Sienerth, K.D.

Instrumental Analysis Oxford University Press, 2017. ISBN-13 978-0-19-994231-2. Lab notebook (a composition book is OK as long as the binding is sewn or glued and

the pages not perforated)

Reading Assignment: Hearn, Walter “Whole People and Half-truths” in The Scientist and Ethical Decision,

Charles Hatfield, ed. InterVarsity Press, 1973. (the book is on reserve in the library) Saks, M.J., Koehler, J. J. Science, 2005, 309, 892-895. (this article is available

electronically via the Westmont library).

Course Webpage:

The course Eureka page contains a copy of the syllabus and schedule, experiment handouts, and copies of the Lecture PowerPoints.

F. Method of Grading:

The evaluation segments are weighted as follows:

Formal lab reports 600 points 60% totalFirst lab report, pre-rewrite 50 points 5% totalLab Notebook 300 points total 30 % total Notebook set-up (Title page, TOC, etc…) 25 points (2.5 %) Experimental records (x 11) 275 points, 25 each (27.5 %)One page reading assignment summary 20 points 2 % totalInstrumental problem solving workshop 30 points 3% total _ Total 1000 points 100%Grading rubrics for the notebooks and formal lab reports are given as an addendum at the end of this syllabus.

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Based on the collected score, letter grades are assigned, where A equals an exceptional, B a superior, C an average and D a poor result. I reserve the right to curve the final grades and grades for individual assignments but will guarantee the following letter grades or better if you achieve the following pre-curve point scores:A 92.5-100%A- 90.0-92.4%B+ 87.5-89.9%B 82.5-87.4%B- 80.0-82.4%C+ 77.5-79.9%

C 72.5-77.4%C- 70.0.5-72.4%D+ 67.5-69.9%D 62.5-67.4%D- 60.0-62.5%F ≤59.9%

Incomplete grades will only be considered for medical reasons or significant personal reasons (i.e. death in the family, etc…). Which personal reasons are significant will be determined by the instructor.

G. Course PoliciesGeneral Conduct:As far as possibly, I expect you to conduct yourselves with courtesy, dignity, honesty, and discretion as befitting Christian men and women. This includes but is not limited to honesty in preparation of lab reports, prompt attendance at lectures and laboratories, and diligence in attending to the laboratory safety rules.

Attendance:Attendance at the weekly labs is expected and mandatory. A missed lab will result in a zero for that assignment. Before leaving lab, students should check out with the instructor. This involves verifying that their lab area is clean and presenting their lab notebook to the instructor for grading prior to leaving lab. Laboratory Safety Rules:All students must complete the departmental safety handout/checklist sheet and agree to abide by the departmental safety expectations. A few key points are given below just to emphasize that they are particularly important:

1) All laboratory experiments will be done during the scheduled laboratory periods. The instructor or a teaching assistant must be present during the time work is being done.

2) Safety glasses or goggles must be worn at all times in the laboratory.3) Gloves should be used for all procedures in which chemicals are handled.4) No shorts or open-toed shoes are allowed in the laboratory.5) Eating and drinking are not allowed in the laboratory.6) Do not do anything you know or think might be unsafe. If you are unsure about the

safety of any procedure, stop and ask for guidance before proceeding.7) Clean up spills (especially of acids and bases) as soon as you can and let others know

they are there so they can avoid them. Dispose of broken glassware in glass containers.

8) Dispose of used materials in appropriate containers, not down the drain, unless directed otherwise.

9) Clean up your lab area before leaving for the day. Leave it as you found it.

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Lab Reports:Formal reports (FRs) for each laboratory are due at the end of the next class session following the lab. Reports should be submitted both in hardcopy and as pdf files so that the instructor can annotate them electronically (e.g. legibly).

When preparing your reports you are encouraged to work with other students to discuss the experiments and data analysis. However, all submitted written work must be your own (see the academic dishonesty policy below for more details). Linear regression, standard deviation, and graphing techniques will not be directly taught in this course since these are covered in other lower division chemistry courses. However, since you are expected to use them in your data analyses as appropriate I would be pleased to provide you with one-on-one instruction in any of these techniques. Just let me know and I’d be happy to arrange a time when we can meet for this purpose.

In the instructor’s experience science writing is best learned in a coaching relationship. Because of this I highly encourage you to meet with me one or more times throughout the semester to discuss particular graded lab reports or lab report drafts. I would even be glad to grade one or two of your lab reports in your presence and explain the reasoning behind my comments and grading procedures. In either case, please plan at least 30-45 minutes for these meetings. They might take considerable time but in my experience they are one of the most effective routes to improvement.

Late Lab reports will incur a 25% per day grade reduction. Since this is generally more than you are likely to lose due to a complete but imperfect lab report you are highly encouraged to submit even noticeably imperfect reports on time as long as they are complete and you are reasonably sure your data analysis is correct.

Lab report rewrites:A significant part of this course involves learning how to think deeply about laboratory science and communicate it effectively and professionally. Doing this takes practice and is best learned in the context of a coaching relationship with one or more professional scientists. Not infrequently, failure is the royal road to success. You might even find one or more of your “best effort” lab reports returned with many critical comments and a less than stellar grade. If this happens to you have no fear. This class provides a reasonable safety net to allow you room to learn from your mistakes without undue harm to your final grade. Not only will lab reports be returned one week before the next one is due; you’ll have two opportunities to rewrite lab reports. First, you are required to revise one of your first two lab reports based on feedback you receive on your initial drafts. In that case the rewrite will be worth the points of a full lab report and the initial draft much less (30% of what a normal report contributes to your overall grade). Second, you will have the opportunity to rewrite any one lab report for a regrade; in that case the average of the rewrite and original lab report grades will replace the original grade you received. You may do this for any lab, including the one your originally rewrote.

Electronic equipment (cell phones, laptops, calculators, etc...):Electronic equipment may be freely used during lecture and labs as long as they do not distract the attention of other students. All lab records, aside from instrument data graphs

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and reports, must be recorded in the laboratory notebook. As far as possible, please leave the room to conduct or receive phone calls.

Academic Dishonesty:Evidence of academic dishonesty, including plagiarism and falsification of data, will result in a zero for the particular assignment. A second offence will result in withdrawal from the course with a grade of F. As per Westmont college policy all instances of academic dishonesty will be reported to the provost’s office for possible further action at their discretion.

Note that plagiarism covers more than verbatim copying of material; it can include copying another student’s flow of thoughts and ideas. Consequently those of you who work with other students when writing your lab reports are particularly invited to read Westmont College’s plagiarism policy for guidance (https://classic.westmont.edu/_offices/provost/plagiarism/plagiarism_policy.html) and to talk with the instructor about any doubtful cases that might arise.

Disability/Medical:Exceptions to the course policies will only be considered for disability reasons or serious sudden medical or personal emergencies. Students who have been diagnosed with a disability (learning, physical or psychological) are strongly encouraged to contact the Disability Services office (Please contact the Director of Disability Services, Sheri Noble (snoble@westmont.edu) as early as possible to discuss appropriate accommodations for this course. Formal accommodations will only be granted for students whose disabilities have been verified by the Disability Services office. These accommodations may be necessary to ensure your full participation and the successful completion of this course. Serious sudden emergencies must be documented and discussed with the instructor within one week of the student’s return to campus.

H. Disclaimer:The course schedule, topics, assignments, tests, and lab exercises presented in this syllabus are offered in good faith. However, these may be changed at the instructor’s discretion with the caveat that additional assignments, tests, and quizzes will not be capriciously imposed on the students.

1) This syllabus and lab report guidelines are adapted and expanded from those written by M. Masuno (2007), N. Tro (2006), and M. Nishimura (1995).

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I. Tentative Course Schedule

Since this course emphasizes problem solving and experimental design it does not have a traditional schedule. Instead, you’ll just be given a series of problems to solve which you’ll attempt one after the other. In some cases a problem will take you only one week to complete while in others it may take several weeks to obtain sufficiently trustworthy results. At various points throughout these exercises you will be given laboratory handouts to use as a starting point for your laboratory work; at other times we will work together as a class to develop our own plan for moving forward. The problems are:

1. Can pohotolysis be used to convert cis-azobenzene to trans-azobenzene or vice versa?

2. Writing professional quality articles – a lecture, discussion, tips, and tricks.

3. Do Sunkist and Mountain Dew contain more caffeine and benzoic acid than the FDA permits?

4. Can we remove heavy metal pollutants from water using surface-modified nanoparticles?

5. Why did a steel beam fail?

6. How effective is a new xylene isomerization catalyst at producing p-xylene from a petroleum-derived mixtures?

7. How do synthesis conditions affect the molecular weight distribution and viscosity of polystyrene?

8. What complexes form between Ni2+ and ethylenediamine in aqueous solution?

It is unlikely we will successfully complete all of these projects. Right now the plan is to work through these projects in order, although depending on our progress the schedule may be rearranged.

Final Exam period Chemical Analysis Problem-Solving workshop activityBased on your section you will attend one of the following:Section 1 only: Wednesday, Dec. 13th, 8 – 10 AM: Chemical analysis problems workshop

Section 2 only: Wednesday, Dec. 13th, 12 – 2 PM: Chemical analysis problems workshop

Optional assignment: I will accept a rewrite of any one of your lab reports (including the one you rewrote before). In this case the rewrite grade will be averaged with the original lab report grade. You may complete this at any time but I will not accept it after the Thursday final exam period.

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Advanced Analytical Chemistry Expected Schedule (This schedule is not typically made public in order to provide students with a more realistic laboratory experience; here it is provided for program review use)

Week Experiment

Aug 30 Course orientation & Can pohotolysis be used to convert cis-azobenzene to trans-azobenzene or vice versa?

Sep 6 How to write Scientific papers lecture and guidelines; ask students to write up the soft azobenzene photolysis paper

Sep 13 Spectrophotometric Analysis of Caffeine & Benzoic Acid in a Soft Drink: Part 1- the Two-Component Mixture Analysis. Note that this experiment will generate systematically erroneous results. The idea is that the students will learn to recognize and rectify this problem.Article/report for the azobenzene photolysis project is due

Sep 20 Analysis of caffeine and benzoic acid in a soft drink debrief (with goal of coming up with multicomponent mixture analysis); then students work as one big group to redo the lab as a multicomponent mixture analysis – i.e. make calibration curves for various dyes, citrate, and isocitrate, assuming other components don’t absorb much)Spectrophotometric analysis of caffeine and benzoic acid in soft drinks report is due

Sep 27 Continue data analysis and check the multicomponent mixture analysis using the GC-MS isotopic dilution method; introduce the nanoparticle analysis lab and get students started on the nanoparticle synthesis

Oct 4 Soft drink analysis debrief and experimental evaluation of nanoparticles’ ability to remove ions from polluted drinking water using AASUpdated/more extensive report for the soft drink analysis is due

Oct 11 Fall Holiday – No Lab

Oct 18 Nanoparticle water purification debrief & Introduction to the Why did the Steel beam fail? lab and Mn in steel sample preparation (give students strength test data for a Mn-containing steel and ask them to assess why a steel beam might have failed by analyzing the %Mn in the steel and seeing if it agrees with specifications.

Oct 25 AAS and UV-vis analysis of the Mn in steel samples along with numerical analysis of the data collectedArticle for the nanoparticle water purification is due

Nov 1 AAS analysis of Mn in steel debrief and How effective is the xylene isomerization catalyst at producing p-xylene? Introduction and FTIR &

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NMR Determination of “before” and “after” xylene mixtures – FTIR and NMR analysis of o-, m-, and p-xylene and two mixtures

Nov. 8 FTIR & NMR Determination of “before” and “after” xylene mixtures – finish the NMR & FTIR data collection and data analysisArticle for the Mn in steel analysis is due

Nov. 15 FTIR & NMR determination of another unknown mixture – this time a BTX mixture containing only o-xylene, p-xylene, and toluene using deconvolution

Nov 22 FTIR and NMR Determination of an Unknown o-Xylene and Toluene Mixture data analysis & introduction to How do synthesis conditions affect the molecular weight distribution of polystyrene Part 1: Polystyrene synthesisArticle for lab the FTIR & NMR determination of an xylene isomerization catalysis is due

Nov 29 Part 2: Polystyrene sample preparation and GPC analysis; standards and unknown

Dec 6 Reading reflection papers, course evaluations, and clean upArticle for the polystyrene MW distribution lab is due

Final Exam period activityBased on your section you will attend one of the following:Section 1 only: Wednesday, Dec. 13th, 8 – 10 AM: Chemical analysis problems workshop

Section 2 only: Wednesday, Dec. 13th, 12 – 2 PM: Chemical analysis problems workshop

Optional assignment: I will accept a rewrite of any one of your lab reports (including the one you rewrote before). In this case the rewrite grade will be averaged with the original lab report grade. You may complete this at any time but I will not accept it after the Thursday final exam period.

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Lab Notebook and Conduct Grading GuidelinesThe following are the minimum expectations for notebooks in Advanced Analytical Chemistry:

All pages in the lab notebook should be sequentially numbered and signed by you & your lab partner when complete.

The lab notebook should contain a title page, table of contents, and entries for each experiment.

The title page should be the first page and should contain your name, the name of the course, instructor name, and the start date covered by the notebook.

The title page should be followed by 3-6 pages devoted to a table of contents. The table of contents pages should contain tables showing each experiment’s date, title, and page numbers.

The experiment pages should contain subsections, namely o a descriptive title, o short (2-3 line) introduction/headingo procedure or description of the work done (which may be cut out and pasted in

from the lab instructions and subsequently emended)o a record of any observations and results (as appropriate including cut and

pasted spectra, chromatograms, and instrument-generated data tables as well as figures made using Excel or other data analysis software) along with any relevant conclusions, hypotheses, suggestions for future work, etc.. It is essentially a rougher and less structured version of the results, discussion, conclusions, and supplementary information sections of a formal lab report. It will be scored based on how well it accomplishes the goals of those sections with much much less attention will be given to the clarity, flow, and effectiveness of the writing itself.

Errors should be crossed out, initialed and dated. All pages should be dated at the top. All pages should be signed and dated at the bottom by yourself and at least one

witness (i.e. your lab partner or another student who witnessed you do the work). Unused space on each page should be crossed out prior to their being signed. All writing in the lab notebook should be legible.

Deadlines and due dates:1. The title and table of contents pages should be completed prior to the second class

meeting.2. The due dates for lab notebooks are as follows:

Start of 2nd Class meeting: The title and table of contents pages should be completed.

Start of each class: Each experiment’s introduction and procedure sections should be completed. If any changes are made to a procedure during the lab period, these should be noted in the margin next to the procedure, initialed, and dated. These should be available for instructor inspection during the lab period.

By the end of each class: All observations and results obtained in lab (but not necessarily all the processed and interpreted results) should be recorded and shown to the instructor for grading as part of each lab’s check-out procedure.

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By the start of class on days when entries are to be assessed: The complete notebook entry, including the analyzed data, evaluation of the results, and main conclusions should be ready for grading by the instructor.

No late notebook entries will be accepted.

Lab Notebook Grading Rubric:

A clear title is given; the table of contents is up to date _____/1 pointComments:A 1-3 sentence introduction clearly explains the work’s significance _____/3 pointsComments:

The entry provides a clear and complete experimental procedure _____/2 points

Comments:

All pages are numbered, signed, and kept correctly _____/1 point

Comments:Mistakes are crossed out with a single strikethrough and initialed _____/2

pointsComments:The lab group used reagents efficiently and cleaned up their area before leaving _____/1

pointComments:

Observations and data are recorded neatly in clearly annotated tablesand graphs, framed with enough text to allow a reader to easily grasp how they fit into the study you performed. _____/5 pointsComments:

The main results of the work are summarized, explained, and discussed with reference to the work’s initial goals – namely those outlined in the 1-3 sentence introduction of the work’s significance _____/3 pointsComments:

The main conclusions of the work are summarized in such as fashion as to allow a cursory reader to look at the end of the entry and rapidly

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grasp your study’s main findings. _____/2 pointsComments:

Was your data analysis procedure reasonable and your results appropriately precise and accurate? _____/5 pointsComments:

_________________________________________________________________________________________ _

Total _____/25 points:

Other Comments:

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Sample Title & Table of Contents pages:

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Sample introduction & procedure:

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Lab Report Grading Rubric

Lab reports will be graded using the following rubric. All sections will be assessed primarily based on how effectively they

1. accomplish the goal of that section (i.e. meet the expectations of a scientific audience and follow scientific writing conventions) ,

2. Employ clear, logically consistent, and artful prose, specifically to Communicate the central messages that section is designed to convey Portray your work as significant, purposeful, and inviting Appropriately offer insightful arguments supported by relevant and substantive data Organized and artfully present your work in ways that makes it easy for readers to

understand, evaluate, and grasp your strategic vision, experimental methodology, and the content and significance of your key findings.

Although word economy will play an increasingly important role as the semester progresses word economy in itself is only of value to the degree it helps you accomplish the above goals.

In addition, your reports will be graded based on the accuracy of your findings. In the event your findings are inaccurate, imprecise, or misleadingly communicated you will receive partial credit based on the degree to which you correctly analyzed your data.

Breakdown:

Complete & appropriately-written sections /65

Abstract /10

Introduction /10

Materials & methods /10

Results and discussion /20

Conclusions /10

Supplementary material /5

Were your results appropriately accurate and precise? If yes then you receive 35 of 35

points

-or-

If not, then based on the degree to which you correctly analyzed your data you may receive /up to 15 of 35

points

Total: /100 points ( %)

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Formal Lab Report Tips“Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.” - Strunk and White, in The Elements of Style

Your success as a scientist (or in any other career) will depend in part on your communication ability. I will grade your lab reports based on content, results, grammar, and style. So please write carefully, revise often, and make every word count.

The lab reports in Advanced Analytical Chemistry will be written as journal articles rather than traditional lab reports. This means that you may have to resist the urge to write your report like a lower division lab report. Crudely, lower division lab reports are all about communicating how well students understand the concepts involved in a particular experiment. Thus they often emphasize theory, experimental background, and thoroughness at the expense of visionary context and organized descriptions of experimental work. There is nothing wrong with traditional lab reports like these; in fact we use them in general chemistry labs to assess student competence. However, a professional journal articles serve a somewhat different purpose. Journal articles are not written to communicate your personal competence but rather to communicate your findings in such a way as to meet the need of a particular scientific community or communities. However, you will still need a deep understanding of each experiment to insightfully and artfully communicate your findings.

There are two reasons you should embrace journal article style reports over lower-division lab reports. First, journal articles better reflect how scientists communicate, think about, and discuss their findings. In this respect professional technical writing will give you some practice engaging in genuine scientific discourse about your lab work. As science majors you should buy up every opportunity you have for engaging in scientific dialogue of this sort. Second, although anyone can write a journal article you may journal article style writing more in keeping with the Christina ethic of neighbor love since is more deliberately other-centered. In order to help other people understand your work you will need to constantly ask yourself what your readers need at a given moment. Moreover, you may find that actually giving readers what they need involves some element of personal vulnerability and risk. Specifically, you may need to leave out the sort of explicit description of background knowledge and theory that most securely communicates your knowledge of textbook instrumental analysis. Rest assured that when you do so you are assuming the risk of neighbor love.

Journal articles differ slightly from field to field and journal to journal. Nevertheless all contain a title, introduction, and some sort of experimental methods, results, discussion, and conclusions sections. They are also summarized by an abstract which gets put in databases like SciFinder Scholar and so will be much more widely read than the article proper.

The general flow and internal logic of the scientific article will be described in the second class of the semester. The following guidelines are intended to supplement that discussion and provide additional tips and that you may find useful as you prepare lab reports

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throughout the semester. In fact, you might want to them just before and after you write your first lab report.

Note: Since these tips will be discussed at the course’s writing workshop the following pages are intended to help you take notes, not serve in place of notes.

The AbstractThe abstract is a brief 1-4 sentence summary of your work (i.e. not background information) and main conclusions (e.g. for your first experiment the main conclusion is the amount of caffeine in the soda can, not caffeine’s extinction coefficients or absorption maxima). The abstract should be completely self-contained and understandable without reference to the main text.

Abstract Tips

1) Write the abstract last – after you have figured out your main conclusions and are prepared to summarize your work.

2) Because you are writing the abstract “out of order” it’s often easy to forget to write it at all. This is not only embarrassing but bad for your grade. I recommend you use the grading rubric (at the end of these guidelines) as a checklist to make sure everything your report is complete you hand it in.

3) Make sure the abstract is complete and completely understandable without reference to the rest of your paper. It shouldn’t assume that the reader is familiar with background knowledge, methodological details, figures, or any other information given in your paper proper.

4) Nevertheless this is not to say that the abstract should include any of all of background, methodological details, and figure information in your report. It just needs to summarize the main features of your work and give your main findings and conclusions, ideally in enough detail to allow a reader to appreciate their significance.

5) Otherwise don’t worry about your abstract being to short. As long as it summarizes your work and gives your main findings and conclusions it is OK.

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The Introduction SectionThe introduction section is a brief (1-3 paragraph long) overview of the experiment that orients readers and draws them into the rest of the report.

Most introductions accomplish three goals:1. Introduces/explains the broader significance of the work (i.e. answers the “Why did

you do it?” question). This part often reviews pertinent background information in an attempt to define a specific problem.

2. Clearly explains the question addressed and delineates the scope of the paper (what was done). This part essentially defines the topic of the paper, clearly states the problem you are seeking to address, or otherwise tells the reader what the paper is about.

3. Introduces the experimental strategy employed (“What technique did you use and why?”). This part of the paper tells the reader what experimental strategy or technique you used to address the problem your work addresses. It should include enough detail to allow your reader to understand your strategy and prepare them to read the rest of your paper.

If you addressed the three goals sequentially but still connect them together you will have the opportunity to mentally “funnel” your reader into an understanding of what your paper is all about. By funnel I mean that you will help your reader move from an understanding of the broad significance of your work to a grasp of the specific problem you are addressing and onward to an understanding of the specific approach you used to address the problem. At its most crude you can think of the three goals as corresponding to three paragraphs:

Paragraph 1: Introduces to the issue your paper addresses in its broadest significance and then develops it in increasingly specific detail until the specific problem to be addressed is clearly defined so that …

Paragraph 2: Gives a clear statement of the paper’s scope … Paragraph 3: …On the basis of which the overall experimental strategy employed

in the paper can be explained.

Introduction Section Tips1) Don’t summarize, introduce. Introduction sections are introductions, not a summary of

what you did.

Poor: “Volumetric pipettes are useful for measuring the volume of a liquid used in an experiment. In this experiment we will use a 10 mL volumetric pipette to deliver aliquots of water into a 50 mL Erlenmeyer flask. The mass of each delivery was then determined using an electronic balance and corrected for buoyancy using equation 1.

(1)

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mactual=mobs(1−dair

dcalibrationweights

1−dair

dwater)

The density of water at 20˚C was then used to determine the average volume of water actually delivered by the pipette.”

Better:“Volumetric pipettes are useful for measuring the volume of a liquid used in an experiment. Because of inconsistency in the pipette manufacturing process manufacturers are only able to guarantee the volume delivered by each pipette to a specified tolerance. In order to use individual pipettes to perform more accurate measurements it is necessary to calibrate them by measuring the amount of liquid each delivers. In the present work, a 10 mL pipette was calibrated by measuring the average mass of water it delivers. Mass measurements were chosen for the calibration since masses can be measured more accurately and precisely than volumes.”

2) Your introduction should begin by outlining the problem of broad significance that your work seeks to address. This problem typically involves the system under study (e.g. caffeine in soft drinks) and not the experimental approach per se. This means you will rarely start by describing the instrument or technique you used. Instead describe what you are studying (e.g. caffeine in soft drinks, indicators, etc…).

3) Do not confuse the introduction section for your paper with the introductory comments in the lab handout or the prelab lecture. Lab handouts and prelab lectures serve to get students ready to learn from a lab experience, often by introducing new techniques (or new aspects of familiar ones) and/or clearly laying out the specific problem to be solved. In contrast the introduction section of a paper introduces the problem a body of work addresses, lays out the scope of the work described in the paper, and provides readers with a vision of the experimental or theoretical strategy employed. It may be helpful to consider an example:Humorous Poor example:“UV-vis is a terrible technique for analyzing some mixtures. Atomic absorption spectroscopy can be even worse sometimes. In these cases it can be useful to try infrared spectroscopy because it gives sharper bands or to try high-field NMR spectroscopy because it tends to give widely-separated peaks. I know the connection between what I just said and what I’m about to say might not make much sense but in the present work the composition of a mixture of o- and p-xylene was determined.”

4) Sometimes the lab handout and prelab lecture do not outline the problem of broad significance. This is deliberate. In these cases you should use the information literacy skills that you learned about in organic chemistry and other foundational classes to learn more about why it might be useful to undertake analyses similar to those you performed in lab.

5) Don’t steal your own thunder. The introduction should not contain experimental details, results, or other material you will present in subsequent sections of your report. Corollary: If you find you have nothing to talk about when you are writing your Results and Discussion section you may have included too much in your introduction.

6) Avoid detail and over-preoccupation with theory. Make sure everything you say supports one or more of the goals of the introduction section. If it doesn’t leave it out. You can always put information that doesn’t fit in the body of your paper in the supplementary materials section if you need to.

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7) Use clear transitions as you move from one goal to the next. For instance, at some point your introduction should tell the reader what you are studying and what your paper is about. When you do this be sue to let the reader know you are not talking about background material any more by using phrases like “Herein…”, “In the present work…”, etc…to set your work off from background material.Poor example: “…Bromothymol blue is an acid-base indicator that changes from yellow to blue on loss of a second proton as the pH is increased from six to eight. The midpoint of this transition roughly occurs when the pH is equal to Bromothymol blue’s second acid dissociation constant, pKa2. Thus knowledge of the pKa2 permits the indicator to be used more accurately as an optical pH probe. The value of this dissociation constant was measured by following changes in Bromothymol Blue’s absorption spectrum as a function of pH. …..”Better but still lacking: “…Bromothymol blue is an acid-base indicator that changes from yellow to blue on loss of a second proton as the pH is increased from six to eight. The midpoint of this transition is roughly occurs at when the pH is equal to Bromothymol blue’s second acid dissociation constant, pKa2. Thus knowledge of the pKa2 permits the indicator to be used more accurately as an optical pH probe. The purpose of this experiment was to measure the value of Bromothymol Blue’s second dissociation constant by following changes in its absorption spectrum as a function of pH. …..”

8) Emphasize things that are worthy of emphasis. For instance, you may be wondering why the 2nd example under #4 is identified as still lacking when it clearly distinguishes between previous work and the present study. The reason has to do with its emphasis on the “purpose” of “the experiment” in the topic position. In other words, the second example makes the idea of purpose the “topic” rather than the specific purpose itself the topic. It is better to just make that purpose the topic in the first place. An improved version of the previous example may help make this clear:Improved revision: “…Bromothymol blue is an acid-base indicator that changes from yellow to blue on loss of a second proton as the pH is increased from six to eight. The midpoint of this transition is roughly occurs at when the pH is equal to Bromothymol blue’s second acid dissociation constant, pKa2. Thus knowledge of the pKa2 permits the indicator to be used more accurately as an optical pH probe.In the present work, the value of Bromothymol Blue’s second dissociation constant was measured by following changes in its absorption spectrum as a function of pH. …..”

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The Materials and Methods Section (sometimes called the “Experimental” Section)

The materials and methods section is a concise but appropriately-detailed account of the procedure you followed and techniques you employed to obtain your results. It should not contain a “step by step” account of your procedure but rather give a succinct and well-organized description of the work performed that

(a) Contains enough detail to enable a professional chemist (but not necessarily a lower-division undergraduate student) to reproduce the results.

(b) Focuses the reader’s attention on the most important details of the experiments rather than the physical movements of the experimenter and experimental apparatus.

Flawed example (focuses on what happens to a “flask”):“A 250 mL roundbottom flask was successively charged with a stir bar, 100 mL tetrahydrofuran, 9.31 g (0.100 mol) of aniline and 7.85 mL (8.64 g, 0.110 mol) acetyl chloride. The flash and its contents were then heated to 50°C for four hours.”

Better (focuses on combining the reagents):“Aniline (9.31g, 0.100 mol) was mixed with 100 mL tetrahydrofuran and then treated with 7.85 mL (8.64 g, 0.110 mol) acetyl chloride. The resulting mixture was then stirred vigorously and then heated to 50°C for four hours.”

More Materials and Methods Section Tips:1) Organize then summarize. By all means avoid giving a chronological “blow by blow”

report of every manipulation you performed during the entire lab period.2) Organize. Often organization by topic (sample preparation, measurement, data analysis,

etc…) makes more sense than a strictly chronological account. The “MEN” scheme often works well. It involves separate subsections for M aterials/standard and sample preparation E quipment/Instrumental analysis N umerical analysis/Data analysis

3) The MEN organization works well as an organization scheme but doesn’t necessarily

make for good subsection titles. As far as possible give each subsection(or sub-subsection) an italicized heading that is descriptive and specific (e.g. instead of using “materials” say “Calibration standards.”Example: Calibration standards: A 0.100 M standard stock solution of compound A was prepared by dissolving 125.1 mg of compound A in 50.00 mL 1.0 M HCl and then diluting the resulting mixture to the mark in a 100 mL volumetric flask. …”)

4) Organize within each subsection. For instance if you prepared calibration standards and an unknown sample describe them in separate paragraphs or sentences of the materials subsection.

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5) Use conventions to avoid unnecessary detail. Since you may assume that your reader is familiar with the technical material covered in undergraduate Chemistry courses you do not need to explain the details of common lab techniques.Poor Example: The groundwater samples were clarified by pouring each solution into 1000 mL scale 0.45 micron filters and collecting the liquid that flowed through when a vacuum was applied. Better:The groundwater samples were clarified by vacuum filtration using 0.45 micron filters.

6) Summarize and under no circumstances give a “blow by blow” account of what you did in the lab.Poor example:Sample preparation: Compound A (125.1 mg) was obtained using a nickel spatula and then weighted out on a 5 cm square piece of weight paper using an Ohaus 800 analytical balance. The weighted sample of compound A was then transferred to a 50 mL volumetric flask and then 50.00 mL of 1.0 M HCl was added using a volumetric pipette. The resulting mixture was swirled to dissolve the solid and then DI water was used to dilute the resulting solution to 100.0 mL. The final solution was inverted and shaken twenty times to ensure it had the same composition throughout.Better:Sample preparation. A 0.100 M standard stock solution of compound A was prepared by dissolving 125.1 mg of compound A in 50.00 mL 1.0 M HCl and then diluting the resulting mixture to the mark in a 100 mL volumetric flask. …”

7) Summarize some more. For example, when describing measurements don’t indicate what was measured if you made all measurements the same way:Humorous poor example: “…Absorbance measurements were obtained for three Bromothymol blue solutions (pH 1, 6.9, and 13) using a Thermo Nicolet eEvolution 300 UV-vis spectrometer. Then absorbance measurements were obtained for an additional seven solutions (pH 4.5, ...). On Mondays, Wednesdays, Fridays, and at teatime absorbance measurements were made using a ThermoNicolet eEvolution 300 UV-vis spectrometer. On Tuesdays, Thursdays, during chapel, and when it was raining absorbance measurements were made using a ThermoNicolet eEvolution 300 UV-vis spectrometer. Red samples were contained in 1-cm pathlength quartz cuvettes and DI water was used as a blank. Blue samples were contained in 1-cm pathlength quartz cuvettes and DI water was used as a blank. The same holds for orange, teal, magenta, cyan, perriwinkle, and all other color samples too.”Better: ”Absorbance measurements were obtained using a Thermo Nicolet eEvolution 300 UV-vis spectrometer. Samples were contained in 1-cm pathlength quartz cuvettes and DI water was used as a blank.”

8) Don’t summarize at the expense of clarity or insight. For instance, feel free to use short phrases explaining why you chose certain conditions or performed particular manipulations if these will help your reader follow the logic of your procedure. Just make sure to do this sparingly.Example: “The filter cake was washed with three 5 mL portions of ice cold methanol; cold methanol was used in order to avoid dissolving significant quantities of the precipitate.”).

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9) Use the numerical analysis subsection well. Often but not always, the numerical analysis subsection should be used to explain the technical details how you analyzed your data. The most common types of things to describe are the details of statistical analysis, regression, curve fits, and other mathematical modeling techniques.

10)…However, do not describe trivial calculations such as dilution calculations or y = mx + b calculations in detail. You can assume that readers of your report can perform simple math. I will check the sample calculations in your supporting information if I think you did something wrong.Poor example:“Data analysis: The absorbance values for the standard solutions were plotted as a function of concentration using Excel. Excel’s trendline function was then used to generate a trendline. The concentration of caffeine in the Sunkist solution was then determined from it’s absorbance at 257 nm by using the calibration curve trendline y = 137356 x + 0.00432. The resulting concentrations were multiplied by a factor of 128 to take into account dilution.”

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Better:“Calibration curves: Trendlines for linear calibration curves were generated using regression analyses carried out in Excel 2003 using the data analysis toolpack.”

12) Do not give any results that you will present and discuss in your Results and Discussion section. It may be appropriate to give trivial or incidental results that are needed to understand your methods in the methods section (like the lab temperature or an excitation wavelength you selected based on UV-vis spectral data). However, never preempt your results section in your methods section.

13) Materials of known composition are called standards. Call them that.Amateurish example:“Solutions of variable zinc concentration were prepared by diluting a 100 mg/L zinc sulfate solution with....”Better:“Aqueous zinc standards were prepared by diluting a 100 mg/L zinc sulfate solution with....”

14)Don’t ascribe agency to inanimate objects like instruments and other lab equipment.

Poor example:“The Thermo-Nicolet eEvolution 300 UV-vis spectrometer measured the amount of Mn2+ in solution.”Better:“The amount of Mn2+ in solution was determined from the permanganate absorbance at 525 nm measured using a Thermo-Nicolet eEvolution 300 UV-vis spectrometer.”

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The Results & Discussion Section or SectionsThis section includes the descriptive presentation of the results you obtained and a discussion of their significance, often with respect to any issues identified in your introduction section. The results and discussion section may be separated into separate results and discussion sections if you prefer. In that case the results section should present and explain key results that you obtained, including key pieces of raw data (e.g. spectra, particular experimental values) and key values that you calculated. The emphasis should be in straightforward experimental conclusions that only need perfunctory or technical explanation. The discussion section should discuss and contextualize the results presented in the results section in the context of the broader scientific and technical literature, the specific problem outlined in the introduction, and, if appropriate, issues of even broader significance.

The results and discussion section or sections should be well-organized so that the results are presented and discussed in such a way as to “tell the story” those results suggest and how they lead to the conclusions given in your conclusions section.

Tips & guidelines for the results and discussion section:1) Keep this section organized. While any order that “tells the story” of your results is OK a

chronological order often works best and is the easiest to write.

2) However, if you use a combined “results & discussion” section instead of a results section good organization should trump chronology. Even though you probably performed your data analysis last it might make sense to present (explain) and discuss (analyze) each set of results before moving on to the next set.

3) The results and discussion section is one of the sections in which you might want to explain the theory needed to understand your analysis in detail. Nevertheless keep your explanation to the point and don’t include extraneous details. The goal of this section is not to present theory per se (unless it is a paper about theory) but rather to support the presentation, explanation, and/or discussion of the results.

4) Organize the results and discussion section around key results.

5) Many professional articles are even written around the results contained in key figures. Thus you should make use of chemical drawings, data tables, graphs and spectra, and equations as appropriate in order to make your discussion as easy to follow as possible. These conventions are outlined below and modeled in the lab handouts used throughout the semester. Please see any scientific journal (e.g. The Journal of the American Chemical Society, Analytical Chemistry, etc…) for additional examples.

Chemical drawings (but not 3D models or crystal structures) should be labelled as schemes, numbered sequentially, and given a scheme caption above the scheme (e.g. Scheme 1. Synthesis of …).

Tables should be numbered sequentially (Table 1, Table 2, etc…) and labeled with a table caption above the table.

Graphs and spectra should be labeled as “Figures”, numbered sequentially (e.g. Figure 1, Figure 2, …), and given a figure caption below the figure. These captions

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are used in place of any titles the tables and graphs may be otherwise given; thus in your paper graphs should not be given titles.

Equations should be numbered sequentially by a right-justified number in parentheses given to the right of the equation and are referred to by equation number in the text.

All captions should have the following format: “Table/Figure 1. Short description of what it is showing.” (.e.g. Figure 1. Absorbance of 1 mg/mL caffeine in 0.1 N sulfuric acid)

These formatting and caption rules should be used throughout the paper, not just in the results and discussion section.

6) An empirical plot of some instrument signal (like absorbance) vs. some composition measure (like concentration) is called a calibration curve or working curve. Call it that in the text and figure captions.

Amateurish example:“Figure 1. Plot of absorbance vs. concentration for zinc standards obtained using atomic absorption spectroscopy.”Better:“Figure 1. Atomic absorption calibration curve for aqueous zinc sulfate.”

7) When presenting results in a Results section or subsection stress results and relationships between results by placing them in the stress position at the end of a sentence.OK example (stresses equality between the intercept value and pKa2):“…The y-intercept in Figure 4 is 7.21±0.06, which is equal to the pKa2.”Better example that stresses the pKa2 value as an important emphasis-worthy result:“… The y-intercept in Figure 4 corresponds to Bromothymol Blue’s pKa2, indicating that its value is 7.21±0.06.”

8) When presenting or discussing results focus on the physical system under study as much as possible.OK example (focuses on the solution):“The dependence of the solutions’ absorbance at 432 nm on solution pH is shown in

Figure 2.”Better example (focuses on the indicator under study):“The dependence of Bromothymol Blue’s absorbance at 432 nm on solution pH is shown in Figure 2.”

9) Use presentation language, not method language to present results.Poor example that restates what is shown in a graph as its topic and uses a “method” verb to emphasize how results were obtained rather than the results themselves:“The log of the ratio of the concentration of Hin- to In2- was plotted against pH as shown in Figure 4.”Better example that makes observed relationships the topic and uses presentation language to direct readers’ attention to graphical results:

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“The relationship between the solution pH and the log of the ratio of the concentration of Hin- to In2- for Bromothymol Blue is shown in Figure 4.”

10)When discussing results, it is often best make your results the subject or “topic” and “stress” the comparison or evaluation by placing it at the end of the sentence.Poor example that makes a literature result the topic of discussion:“The manufacturer reports that a 12 oz. can of Sunkist contains 41 mg of caffeine; our results indicate a higher value of 51 mg per can.”Better example that makes the paper’s results the topic of discussion:“The 54 mg/can caffeine levels obtained for Sunkist are ~50% higher than the manufacturer-reported value of 41 mg/can.”

11)It may not make sense to present every single data point, spectrum, or graph you obtained. When you have sets of spectra or other data consider giving a representative data set or spectrum (to give your audience an idea of your data quality) and a summary table. Additional raw data or sets of spectra can always be placed in a “supplementary materials” section at the end of your report.

12)If you use a separate results section don’t forget that “results” include calculated values (concentrations, pKas, etc…) in addition to your raw data. Because of this the results of your calculations should be presented and explained in the “results” section, although the calculations may be discussed in the “discussion” section if such a discussion might help the reader better contextualize your results (e.g. “Because the analysis employed ignores the contribution of the colorants present, the concentrations of caffeine and benzoic acid we obtained are likely overestimates. This is because the extra absorbance is ….”

13)Avoid minutiae that can disrupt the flow of the presentation and discussion of your results and/or be perceived as unprofessional. For example, you should assume that your reader has a good grasp of basic math and avoid mentioning trivial calculations (dilution calculations, y = mx +b, etc…) in any detail. To the extent they show up in the results section at all they are often implied. Again, I’ll check the sample calculations in your supporting information if I think that you did something wrong.Poor example:“The water in cold spring creek gave an atomic absorbance signal of 0.352 units; according to the calibration curve equation of 0.002 units + 0.175 units-L/mg x concentration this corresponds to a concentration of 2 mg/L zinc.”Better:“The water in cold spring creek gave an atomic absorbance signal of 0.352 units, corresponding to 2 mg/L zinc.”

14) When you clearly have erroneous results or suspect that a specific error occurred you should note this and explain how it affects the reliability of the measurement. However, don’t try to postulate the existence of error as a sort of disclaimer for why your results are unlikely to be accurate to the fortieth decimal place or otherwise make up sources of error. Only mention sources of error when you can explain why you think your results might be in error.

15) When comparing a result with the literature or theoretical expectations, be specific. Indicate whether your result agrees with, is greater than, or is smaller than the literature value.

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Bad Example:The pKa of Bromothymol blue was found to be 7.15±0.03 which can be compared with the 7.10-7.30 range of values reported in the literature. Better:The pKa of Bromothymol blue was found to be 7.15±0.03 which falls within with the 7.10-7.30 range of values reported in the literature.

The Conclusions SectionMany journals do not have a separate conclusions section; rather the conclusions are given at the end of the results and discussion section. However, in this class you will use a separate conclusion section.

When present, a conclusions section consists of a 1-3 paragraph summary/restatement of a paper’s main conclusions. For most of the experiments in Advanced Analytical Chemistry the conclusions section will be quite short and simply involve stating the value of a measured parameter and its error (e.g. 125±3 M caffeine in brand X soda). However, results should always be placed in the context of the problem outlined in your introduction when it makes sense to do so. In addition, when you clearly have erroneous results or suspect that a specific error occurred you should note this and briefly comment on how it affects the reliability of the measurement.

Conclusion section tips1) You should only report your main conclusions in this section. These generally relate to

the goal of the experiment (e.g. to measure caffeine levels, not extinction coefficients).2) Do not forget to place conclusions in the context of the problem outlined in your

introduction section. In this connection don’t forget compare your key results to literature, manufacturer-reported, regulatory, and other known parameters and specifications as appropriate.

3) It’s OK to have a 1-2 sentence conclusion section as long as those sentences accomplish all of the conclusion section’s goals.

4) Avoid using error estimates as a disclaimer and don’t make up sources of error. Only comment on errors that are evident from your results or faulty technique you recognized after completing the experiment. In that case, these errors should first be discussed in your results and discussion section and summarized in your conclusions section.Poor “made up disclaimer error” example: Results & Discussion: As can be seen from Figure 2, our calibration curve is highly linear with an R2 of 0.9999 and relative standard errors in the slope and intercept of 0.01% and 0.007%, respectively. The A575 cm-1:A670 cm-1 ratio we obtained using three replicate measurements on independently prepared unknown solutions is 0.7623±0.0004, which corresponds to 35.723±0.009 % toluene in the unknown.”

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Conclusion: “Unknown mixture B was found to contain 35.6±0.9 % toluene. It’s likely that this result is in error due to inaccurate pipetting.”

Better example in which there is a reason to expect a specific source of error:Results & Discussion: “Because the A575 cm-1:A670 cm-1 ratio for the 40:60 (v/v) toluene:o-xylene standard clearly deviates from the otherwise linear calibration curve it’s likely that this standard was incorrectly prepared. Unfortunately, we did not have enough data points to statistically exclude the 40:60 (v/v) standard. Because the slope of the trendline is likely higher than the actual slope, the calculated concentration of caffeine is probably an underestimate.”Conclusion: “Unknown mixture B was found to contain 35.6±0.9 % toluene. However, because of possible errors in the preparation of the 40:60 (v/v) toluene:o-xylene standard, we suspect that the reported volume percent toluene is likely an underestimate.”

Supplementary materialThis is where you will include your raw data tables and any spectra not discussed in your results and discussion section. Where appropriate, provide samples of your calculations.

Some tips and suggestions:1) If you think it is important but it would otherwise disrupt the flow of your article put it

here.2) Be sure to include a sample calculation when appropriate. These aren’t typically

included in professional articles but for the purposes of this class I will use your sample calculation to assess where things may have gone wrong if your results end up grossly in error. That way I can assess how much you did understand the calculations and give you an appropriate amount of partial credit. Don’t rob me of this opportunity. I don’t want you to lose all the data analysis points for what is in reality a small mistake.

3) You don’t need to type out this section. Handwritten calculations and annotated spectra are perfectly OK.

Other tips and Guidelines not related to a Particular Section1. Good articles are clear and concise in that order. Make sure your writing is clear before

you start working on word economy.

2. Most clarity issues can be taken care of by focusing on the main goal of each section and by following the advice in the Science of Scientific Writing handout. The tips below are just additional details:

Clarity tips Write to communicate with a reader, not to show off what you know. Focus on what a

reader expects and needs to know to understand your core message, not on communicating the breath of your knowledge of the underlying chemistry, technique used, etc…

Since numbers without units are meaningless always give units.

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Pay attention to the way technical terms are used while reading the chapter and listening to the pre-lab lecture. This will help you to learn the lingo of analytical chemistry that you will need to describe your results in a professional manner.

Example of incorrect lingo: “The unknown’s absorbancy of 0.453 indicates its concentration is 0.453 M.” Why the previous example is incorrect: A substance’s absorbancy refers to its ability to soak up water (presumably, since no liquid is mentioned). A substance’s ability to absorb light is referred to by it absorbance or absorbance value at a given wavelength. Thus the statement seems to refer to the unknown’s ability to soak up an unspecified liquid. Better: “The unknown solution’s absorbance of 0.453 at 450 nm indicates its 0.0127 M in compound B”

Read your report aloud to yourself before turning it in. You’d be surprised at what the ear catches that the eye ignores.

Have your roommate or a chemistry student who is not in Chm 122 read your report before turning it in. You’d be surprised what a fresh pair of eyes will pick up on.

Word economy tips Be clear before you are concise. Focus on getting the each of the sections of your

report right and using language effectively before shortening them. It is also wasteful of a reader’s time and effort to write something that they will struggle to understand, perhaps unsuccessfully.

Word economy is largely the result of effort and practice. Play the “get rid of words” game with your lab reports (this actually works). Start by going through each section of your lab report and challenging yourself to eliminate 1 word per sentence on average. Then challenge yourself to remove one word per sentence more. Once this becomes really hard you are probably beginning to get the hang of word economy.

Appropriate word economy is best learned by doing. Pay attention to my comments on your earlier reports and learn from them.

Data Analysis TipsData analysis is the single biggest reason students do not get an A-level grade in Chm 122. Poor data analysis not only loses you points on your Data Analysis score, it can lower your Accuracy score to zero as well. Fortunately, data analysis errors can usually be avoided using my rules of common sense.

Contakes’ rules of common sense: You data analysis runs a significant risk of being wrong if:

You didn’t pay attention to units when performing your calculations. I’ve seen several students calculate a correct caffeine concentration in mg/L and report is as mol/L or mg per 12 oz. can because they didn’t pay attention to units.

The value you determine is physically unrealistic. For example, a concentration of 1304±3 M caffeine in Sunkist is probably wrong when one considers that pure water is 55.5 M.

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The concentration you calculate from the equation of a calibration curve doesn’t agree with the value you estimate by looking at the curve.

A value you calculate is an order of magnitude or more off from that given in the literature or from a manufacturer’s reported value. For example, if Sunkist is reported to contain 40 mg or less caffeine per can and you measure 400 mg or 4 mg per can, you should double check your calculations.

Some sources of error to look out for: Order of magnitude errors typically come from mistakes in accounting for dilution or

propagating units. When you are performing curve fits or regression analysis you should plot your curve

fit on the same graph as your raw data to make sure they agree. Excel’s solver tool is extremely powerful but also extremely prone to user mistakes.

Pay attention to the markings on graduated pipettes and be sure to use them correctly. If you “deliver” the extra volume at the bottom of certain mark-to-mark pipettes your calibration curve and every result you obtain from it will be systematically wrong.

Accuracy TipsInaccurate and sloppy lab work is a significant source of error, although usually not nearly as significant as data analysis errors. The key to accurate lab work is to recognize that mistakes happen. The name of the game is quality assurance, which involves taking reasonable steps to prevent, detect, and correct errors as much as is necessary for a given application. As discussed in the introductory analytical chemistry course, much of quality assurance occurs at the level of systems and procedures and is either already embedded in the lab handout procedures or outside the scope of lab exercises like those we’ll undertake this semester. This means that your efforts at improving your accuracy will largely involve how aware you are in the laboratory and how you go about completing each lab. Some tips for doing this well are given below: Tips on preventing mistakes:o Take your time. It usually takes less time to do it right the first time than to rush through

your work and have to do it again. o Be organized and follow a system to prevent mistakes. For example, you could arrange

your flasks in order of increasing concentration and mark them with a sharpie as you add each reagent.

o Pay attention and be aware. Does the level of liquid in each flask agree with what you’d expect? If not, perhaps something is wrong.

o Ask questions when you don’t know how to use a particular piece of equipment or technique. For example, I’ve seen may students make erroneous standards because they used a graduated pipette as if it were a transfer pipette.

On detecting and correcting mistakes:o Analyze your results as you take them and certainly before you dispose of your

samples. That way you can re-make or re-measure samples if you need to.o The anomalies you are seeing in your data often contain clues to what you might be

doing wrong. For example, if a single point falls outside the trend of your working curve, you probably made an error in either making that standard or analyzing it. On the

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other hand, if your calibration curve doesn’t show a clear trend, there must be a significant amount of random error present, indicating that you are almost certainly not doing something reproducibly. In this case, you should review how you made your samples and inserted them into the instrument.

A final tip: Use units when you record results and write out your calculations. Not only are numbers without meaningless, this will help you avoid errors when you make solutions, assess data, and perform calculations.

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Reading Reflection Paper

The purpose of this assignment is to help you to reflect on how the practice of science influences the spiritual and moral development of the practitioner. Read the two articles listed below and write a 1-page reflection paper describing how the points raised by the authors apply to the practice of analytical chemistry. The readings will be discussed and the papers collected during the December 4th class.

First read: Hearn, Walter “Whole People and Half-truths” in The Scientist and Ethical Decision, Charles Hatfield, ed. Intervarsity Press, 1973. (on reserve in the Voskuyl Library)

Then read: Saks, M.J., Koehler, J. J. Science, 2005, 309, 892-895. (Available through the Voskuyl Library print and electronic holdings).

Method of grading. The reflection paper will be graded based on three criteria: (1) demonstrated connection to the readings (8 points), (2) demonstrated application of the reading material to the practice of chemical analysis (8 points), and (3) clarity and logical rigor (4 points).

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