C126 Experimental Chemistry II

Fall 2003

 

Lead Instructor                     

Dr. Gavin Kirton Office: LD 326 Phone: 274-0052 Email: gkirt@chem.iupui.edu Office Hours: By Appointment

Course Meeting Times and Location

Laboratory Sections

B048   9:30am ­ 12:20pm      T                                LD 227

B049   9:30am ­ 12:20pm      T                                LD 275

B050   9:30am ­ 12:20pm      R                                LD 275

Pre- or Co-requisite and Dropping Procedures

C106 is a pre- or co-requisite for participation in C126. For this reason if you drop C106 you must also drop the C126 lab. You are reminded that if you drop the lab you must check out of your drawer or you will incur a $5 charge from the Bursar’s office.

Required Materials

1.     Experimental Chemistry II: Laboratory Manual for C126, Fourth Edition

 

2.     Safety goggles: Approved goggles are available in the University Bookstore and may also be available from the Chemistry Club.

 

3.   Laboratory Research Notebook: 8.5 x11 inch, quad-ruled, duplicate pages. Approved notebooks are available in the University Bookstore and may also be available from the Chemistry Club.

 

4.   A padlock.

 

5.   A general chemistry textbook for reference. Your C105/C106 textbook will suffice.

Your Responsibility

It is your responsibility to come to laboratory prepared. You must be aware of the course policies and procedures regarding attendance and grading. You must keep your graded lab material in your possession until you are certain your grades have been properly recorded. Twice during the semester you will be given a list of the scores the lead instructor has recorded for you. You should check the recorded grade against the actual score on your lab report to ensure the score was recorded correctly and that you have no missing grades.

Examinations A mid-term exam and a final exam will be given. The mid-term will be given during the laboratory lecture period on March 4 and March 6. The final exam date will be May 6 and May 8 as stated in the back of your lab book. Both of these exams will be comprehensive and will test the depth of your understanding of the experiments.

 

Computer Experience

In this class you will rely heavily on computers to work up your data and prepare your lab reports. There are computers available for student use in SL 070 and in the library. You are expected to be familiar with Excel. Make sure that you seek assistance if you are not familiar with Excel.

 

Notebooks and Reports

Notebooks You will turn in all notebook pages for most experiments. Your notebook pages must be complete. That is, they should contain introductory material including a purpose, a procedure and an observation section where you record in explicit detail what occurred while you were carrying out the experiment. Your notebook should also include any post-lab data analysis and calculations performed. Literature values and references should also be included. You must have your TA initial your work in your notebook at the end of each laboratory period. Notebook pages are worth 20 points.

Report Sheets For some experiments you will be required to turn in a Report Sheet. The report sheet will be given to you once you obtain your TA’s initials in your notebook. The report sheet will consist of focused questions that when answered correctly will emphasize important results. Space and/or tables will be provided for you to enter your results and show sample calculations when appropriate. The Report Sheet will be worth 30 points.

Formal Reports When an experiment requires a Formal Report, it should contain the following sections: Title, Introduction, Experimental, Data, Results/Discussion and References. Refer to the handout for a discussion of what each section should contain. Graphs and data tables should be numbered sequentially, referred to by number, and attached at the end of the report. Calculations are performed in your lab notebook. Only the results of the calculations are summarized in tabular form in a report. The Formal Report will be worth 50 points. Formal reports must be typed, 5 pages maximum, 1.5 line spacing, 1 inch margins, 12 pt font, 8.5 x 11 inch paper.

 

Laboratory Notebooks (General Information)

A key element to becoming a good scientist is developing the necessary note-taking skills. Good note keeping skills are acquired and require much practice. These skills can be learned in college laboratory courses; continual practice throughout your college career will ease the transition to the workplace where note keeping, even in non-science careers, is an increasingly critical issue. For these reasons, you will be required to keep a detailed laboratory notebook in all your Chemistry laboratory classes at IUPUI.

The notebook serves as a permanent written record of what occurred in lab. It not only preserves your data and observations but should also contain any analysis and interpretation or ideas you have regarding the experiment. Your notebook must be clear, concise and complete. You must record your failures as well as your successes and write with enough detail and clarity so that someone could repeat your work.

A bound notebook is a must. Pages can be lost or their order scrambled if a loose-leaf notebook is used. Bound notebooks with double sheets are the best. The first sheet (usually white) is written on directly; the carbon copy (usually yellow) can be torn out of the bound notebook and handed in to your laboratory instructor each day. In some courses, you may be asked to submit the originals for grading since they are sometimes easier to read than the carbon copies.

Every page must be numbered. If you prepare a sample, it's a lot easier to write "nitrate/chloride buffer solution, BB:1:22" (your notebook reference) on the label of the sample instead of "0.0362 M NaNO3 + 0.211 M NaH2PO4 in deionized water + 0.2% CHCl3, adjusted to pH 6.64, filtered through a 0.025 mm filter; prepared February 6, 1994". If the detailed information is in the notebook, the sample label can just have the notebook number. The same cross-referencing applies to any plots or print-outs generated in the lab, e.g. spectra or chromatograms.

Always use ink in your notebook; never use pencil! Use a neat format and legible handwriting. Mistakes should be crossed out with a single line.

Leave the first pages of the notebook blank so that a table of contents can be entered later. This can save a lot of time in the future.

Date and sign every page.

All entries must be made when the work is performed. Record your observations and data immediately; don't wait for a lull in the procedure or the end of the lab period. Make sure you include units with your data. Never write notes on scraps, paper towels, etc. for later transfer to the notebook. Always write notes directly into the notebook. The temptation to use a scrap of paper for recording weights while sitting at the balance is especially strong but should be avoided. Even if your notebook is on the other side of the laboratory and you have to walk back to get it, do so!

Graphs and computer printouts should be taped in your notebook.

Each new experiment must be clearly marked with a new heading and should start on a new page. Begin with the purpose of the lab and a research plan. The purpose should include any balanced chemical equations that apply. In a teaching experiment, the research plan can simply be an outline of the procedure or a numbered list of steps to follow. The purpose and research plan should be entered in your notebook before you come to lab. Safety issues should also be noted here.

Record your observations, not just your data, directly in your notebook. If an observation is unexpected, you should take particularly good notes.

Below is a list of items which, when applicable, should go in your lab notebook.

            Chemical reagents

                        Identify the source, who prepared them and when, purity etc.

            Instrumentation

List the manufacturer, the model number and the instrument settings. Sketch the apparatus or experimental setup. Note the materials of construction, seals, flow direction, etc.

            Glassware

            Use specific names, e.g., 100 ml volumetric flask, Erlenmeyer flask, 3 neck-500 ml round bottom flask, not just a flask!

            Cleaning procedures

Example, "glassware was rinsed with DI water, ethanol, and acetone before use"

            Reagent mixing order

            How the reagents were dispensed

                        Were reagents weighed on a balance, or measured by volume?

                        Was a graduated cylinder or volumetric pipet used?

            Accuracy of the balance

            Method for heating or stirring

            Laboratory temperature and humidity

            Elapsed time

                        Record the time at various points throughout the procedure.

            Regulator pressures

            Yields and errors

            Be specific, nomenclature can be ambiguous.

Graphs

            All graphs must have a title and a date; label the axes and include units; use tick marks; use a legend when plotting more than one data set; include error bars if you know the uncertainty; comment on where the data came from.

 

In working up your data you should perform all your calculations in your lab notebook, even if you are no longer in lab. Error analysis also goes in the lab notebook. Once you have completed your calculations you should begin a discussion section where you interpret your results. You "think" in your notebook by jotting down your ideas in prose. Lastly you should draw conclusions, summarize what was done, what was found and the overall goal of the work.

Laboratory Notebooks (Specific Information for C125/C126)

To help you organize your notebook pages and to help the TA’s in grading your notebook we are requiring that you include the following sections in your lab notebook for each experiment. Each section should be clearly labeled.

 

Section 1. Statement of Purpose—in a few sentences state what the purpose of the lab is. This should answer two questions for the reader: What are you doing and why are you doing it. You can also include a brief summary of the procedure to help you gain an understanding of the experiment. This will also help you be more efficient when you actually do the experiment.

 

DO NOT copy the procedure verbatim from the lab manual into your lab notebook.

 

Section 2. Pre-Lab Lecture Notes from your TA. Your TA will review safety items and possibly include last minute changes to the procedure. Specific instructions about equipment and waste handling procedure will often be given at this time.

Section 3. Procedure and Observations—Draw a line down the middle of the notebook page. On the left hand side write out the procedural steps. On the right hand side, write out any observations next to the step in the procedure that they were made. Besides color changes, bubble formation, heat generation, precipitate formation etc., this column should also include weighing data, concentration of stock reagents, type of glassware used if it is significant, etc. (i.e. it is significant when delivering volumes of reagents. Did you use a grad cylinder, a beaker or a pipet?) Lay things out neatly on the page and don't be too stingy with space. Good organization and readability are crucial to keeping a notebook.

 

Section 4. Calculations—ALL calculations should be included in the calculation section. You can paste in output from Excel here. ALL calculations means everything that is listed in the calculation section of the experiment in the lab manual.

Section 5. Literature Values and References—Include any requests for literature values here and the reference from which they were obtained.

 

Lab Reports (General Information)

A lab report is your chance to demonstrate to your professor or TA how well you understand the experiment. A lab report is different than a term paper. It should be written in a scientific style, which is not the same style used for English or philosophy papers. The keys to effective technical writing are organization, brevity, clarity, and an appreciation of the needs of the reader. You must write clearly and be thorough, but concise. Do not ramble. The best way to avoid rambling is to first prepare an outline of the report and stick to it. In some cases results and discussion sections are combined into one single section. Different instructors may have specific formats that they want you to follow. You should always defer to the instructions given to you by your instructor. What is presented here are general guidelines for writing lab reports and scientific papers. The general structure of a lab report follows that of a scientific paper and is given below.

Title and Author (s)

Introduction

Experimental

Results

Discussion

References

Figures and Tables

 

Before writing your first report, visit the library and examine several journal articles. Pay close attention to the style of the prose and the contents of each particular section. A list of several common journals is given below:

 

The Journal of the American Chemical Society

The Journal of Physical Chemistry

Analytical Chemistry

Biochemistry

 

Title State the title of the experiment, your name, the date and your laboratory section number if applicable. Also state who your lab partner(s) was.

Introduction The Introduction states the purpose of the study, providing any background necessary to acquaint the reader with the problem being addressed, as well as providing the reader with references to previous relevant work. Although the Introduction is a portion of a formal report, it is sometimes easier to view this section as a short essay; one in which the writer describes the importance of his work, and the possible application of his work to other areas of interest to the reader. As in an essay, the Introduction begins with a broad description of the principles being discussed in the report, and funnels down, becoming more specific along the way, to a statement of the specific objective of the study. In general, Introductions are 2 to 3 paragraphs long, with the objective of the study being the topic sentence of the final paragraph in the Introduction. In your introduction you will need to choose the relevant facts from your textbook, lab manual or other materials available to you, organize them in your own words, and present them in a logical order that highlights and supports the proposed experiment.

Experimental Here you must give a concise description of what occurred in lab but in sufficient detail to allow the reader to repeat the study. However, unlike the audience for a laboratory text book, the audience for a formal report doesn't need to be told to wash the beakers or to insure there are no air bubbles in the buret tips. It is essential therefore, that the writer be careful not to insult the intelligence of the audience when writing the Experimental section. Another difference between formal Experimental sections and laboratory text books, is that laboratory texts are generally written in second person present tense. i.e. "Open the lab drawer and take out your notebook." Formal Experimental sections on the other hand, are written in third person past tense, i.e. "The KHP solution was titrated with NaOH until a slight pink color permeated the solution." In general, remember that the audience would like to know what was done, not what to do. On a final note, be forewarned that step by step cookbook instructions are unacceptable in formal lab reports. In this section you should always state any observations, give amounts of starting materials and product yields. List reagents used and their concentrations. Give the make and model of any instruments used.

Data and Calculations The first step in completing this section is to work up your calculations and generate any tables or graphs necessary for the analysis. Your data must be presented in a clear, concise manner in order to support any conclusions you will draw from the data. Data may be graphed or tabulated. Whether you graph or tabulate will depend on the data and conclusions you make. You will have to use your judgment. Graphs, tables and figures should be integrated into your text, as you would find them in your textbook or in a journal article.

Results and Discussion When you have finished working up your data, look it over to decide what the data says. State your results briefly, using the past tense. Write something about each graph or table, keeping in mind that graphs and tables present the data but they do not state the results. Do not simply offer the data as your results. Be sure to introduce all your results in this section. Refer to figures and tables sequentially as they are introduced; graphs are considered figures. Figures and tables should be identified with a separate series of numbers. You should also discuss how the reported uncertainty was determined and what was its primary source. This section is the meat of a formal report as it is where you demonstrate your understanding of what you did in the experiment. It is also the most difficult to write, should take you the most time, and is generally worth the most points in your grade.

This section will also contain a discussion of the errors incurred in the experiment as before one can draw conclusions from data one must assess the validity and accuracy of the results. A result is only as good as the accuracy to which it was measured. To evaluate your data you must know how reliable it is. Acquiring data on a brand new instrument does not mean that there is no error in the data, nor are computer calculated results error free. There is always some error in your measurement. Listed below are some common sources of error, all of which should be considered in assessing your data.

Errors in measurement It is easy to misread an instrument, particularly when using an analog device with several scales located on a single meter. Make sure you are reading the right scale. It is common to take 3-5 readings and use the standard deviation of the readings to estimate the uncertainty. Make sure you know what the units are when recording data from an instrument. Other common measurement errors might be miss-reading a buret, not zeroing a balance, or incorrectly taring a balance.

Errors in Recording or Recopying It occasionally occurs that numbers are transposed or decimal points lost when entering data in your notebook or copying them to a table. This type of error is hard to catch unless the number is totally unreasonable or well removed from an observed trend in the other measurements. Examples might be a pH of 23 or a series of repeated measurements where four out of five readings gave values between 0.2 and 0.8, but the fifth reading gave 3.9; clearly there is a problem with the fifth measurement.

Errors in Computation Double check your calculations. Don't assume your answer is wrong if it did not agree with your lab partner's or the literature. Watch your units and unit conversions! Make sure they are consistent. Once you have completed your calculations, consider if the answer is reasonable. Always, recheck your calculations particularly your units before seeking help from an instructor.

Once you have assessed the reliability of your data you can discuss and interpret your results. You should first consider whether you accomplished what was proposed in the introduction and if your results are successful. What are the significant sources of error in the experiment and how might they be minimized in the future?

Even if your results are questionable, it is still possible to write a good lab report. In your discussion you must demonstrate to your instructor that you understand what took place in lab and/or what was supposed to take place in lab. Begin with your interpretation of the results, and then perhaps a comparison of them with expected values. Always try to put a positive spin on your results if possible. You must also discuss the reliability of your data.

Invariably, things will sometimes go wrong in lab, but never begin your discussion with what went wrong. Perhaps begin by stating what should have happened, then discuss what went wrong. It is important that you demonstrate that you understand both what should have happened and what might have gone wrong. Note also that there is a big difference between a null result and a failure to get results.

Always close your discussion by drawing conclusions and relating them to ideas presented in the introduction. Stating that "overall the experiment went well" or that "I learned how to use a piece of equipment" are not strong conclusions. If appropriate, suggest improvements to the procedure, or additional experiments that would test your hypothesis.

Conclusion The purpose of the Conclusion section is to summarize the pertinent concepts discussed in the R & D section, and suggest possible ideas for future study. It is imperative that you restate your results in this section. In other words, if the objective of the study was to determine the percent calcium carbonate in an unknown sample, you should restate the percentage, with its uncertainty, in the Conclusion section. A brief restatement of the possible error sources or important observations goes in this section as well.

 

References Always cite any literature used in preparing your lab report. "Verbal Communications" may also be cited as such. The specific format used to cite references varies from journal to journal. Generally, all citations include the author's last name and first initial, an abbreviated form of the journal title, the volume number, the first page number of the article and the year published. In citing a scientific paper, the title need not be given. In citing a book, begin with the author's name, followed by the title of the book, the publisher, where published, the year published and the specific edition.

 

Examples

N. E. Triggs, M. Zahedi, J. W. Nibler, P. A. DeBarber and J. J. Valentini, J. Chem. Phys., 96, 1822 (1992).

J. A. Halstead, N. Triggs, A. L. Chu, and R. Reeves in Gas Phase Chemiluminescence and Chemi-ionization, A. Fontijn (ed.), p. 307-334, North-Holland, (1985).

 

Formatting Guidelines for lab reports

Clarity and Style Observe the rules of good grammar, spelling, and punctuation. It is expected you will write in complete sentences. Reports must be typed and the use of a word-processor is encouraged. Use 1 inch margins, 12 point font for text and either 1.5 or double line spacing. Choose a font that is easy to read.

Proofread your report before you turn it in. There is no bigger turn off when grading a report than to find sloppy grammar and incorrect spelling. It sets the tone “Expect the worst” and it will surely be reflected in your grade.

Abbreviations Well-known abbreviations, such as cm, M.W., EDTA etc. can be used without explanation. Otherwise, spell out the words the first time they are used, followed by the abbreviation in parenthesis, and use the abbreviation thereafter:

"Potassium hydrogen phthalate (KHP) was used as the primary standard."

Symbols Many quantities have accepted symbols, i.e. pressure (P) or temperature (T). It is often convenient or efficient to define symbols for calculated or measured values.

Equations Equations are presented as part of the sentence structure of the text, and are numbered for future reference. All symbols are defined where first used. In formal reports, the equation, a sample calculation and the results are presented. A very useful tool for inserting equations into your documents is the equation editor available in Microsoft word processor packages.

"The molarity of HCl was calculated from Equation 1, where M and V are molarity and volume (mL) respectively. The mean molarity of HCl for the three trials was 0.0985 M, and the standard deviation, calculated with Equation 2, was ± 0.0002 M."

                                                                                                                   (1)

                                                                                                                       (2)

Remember, each equation is presented only once, and referenced by number thereafter. Equations are not grouped together, but are presented only when needed during the course of discussion.

Graphs The type of graph you draw will depend on your data. Usually in chemistry one uses an x-y scatter plot with the dependent variable on the y-axis and the independent variable on the x-axis. All axes should be labeled--the reader does not necessarily know what you are plotting, and you will be penalized if you leave axes labels out. Be sure to give the units for each axis, for example, "time (secs)" or "Fe³⁺ concentration (moles/liter)". Pay attention to your axes' scales. The same data can look very different depending on how you scale it. Always consider whether it is important to show that your data passes through the origin, or if it is more important that your data fill the scale. Generally on an x-y scatter plot, one does not connect the dots, simply draw the best straight line or curve through the data. If you plot more than one set of data on the same axis, you must include a legend to identify each series. Error bars are also important and helpful in judging the significance of the data. Usually these are only included for the dependent variable.

Tables Tables are used when graphs are inappropriate and the data cannot be introduced in a single sentence of text. Each table should have a title at the top and a table number by which it can be cited in the text. Footnotes are frequently used to convey specifics about a subset of data within the table. Arrange your data in columns rather than rows, it is much easier to read down than across. Do not include a column containing all the same numbers; use a footnote to convey the desired information. Uncertainties in results should be presented with the data in the table.

 

Lab Reports (Specific Information for C125/C126)

Introduction—should acquaint the reader with new ideas and topics discussed in the experiment including definitions of key terms that are new. You must start general and funnel down (basic essay writing technique). Your last sentence and/or paragraph should be a statement of purpose as defined in Section 1 of your notebook.

 

Experimental—Give a synopsis of what went on in lab similar to the brief summary in section 1 of your notebook. In a report you must write in complete sentences.

 

Data—Tabulate your results and introduce them with words in complete sentences.

 

Results/Discussion—Clearly state your results, then discuss the significance of the results. Compare with literature values when possible. Discuss sources of error, suggest improvements. Make a concluding statement(s).

 

References—You should always reference the lab manual. You may have others if you cite literature values or refer to your textbook for clarification of ideas.

Approximate Point Breakdown

Notebook			Formal Report
Completeness	8		Introduction	10
Observations	6		Experimental	5
Organization	4		Data	5
TA Initials	2		Results/Discussion	15
Total	20		Style/Format/Ref	5
			Accuracy/Precision	10
Report Sheet	25		Total	50

Due Dates

Notebook pages and Report Sheets/Formal Reports are due at the start of the stated lab period. Late assignments will be discounted 20% per day that the assignment is late. Tuesday and Wednesday count as one day and weekends count as one day. (A 70 point assignment that is due on Tuesday will be penalized 28 points (2 x 14) if turned in on Friday.) All assignments are due at the scheduled start of class. A 10% penalty will be charged for assignments not turned in at this time. No exceptions!

Total Available Points

Midterm Exam	100
Final Exam	200
Experiments with Formal Reports and notebook pages 2 @ 70 pts.	140
Correction Sheet associated with Formal	20
Experiments with Report Sheets and notebook pages 8 @ 45 pts.	360
Graphing Techniques and Organic 2 @ 25 pts	50
Total Points	870

Grading Scale

Your laboratory grade will be based on a strict grading scale as outlined below. At the discretion of the instructional team, the grading scale may be adjusted when final grades are assigned.

 

A:	93-100%	B-:	80-82.999%	D+:	67-69.999%
A-:	90-92.999%	C+:	77-79.999%	D:	63-66.999%
B+:	87-89.999%	C:	73-76.999%	D-:	60-62.999%
B:	83-86.999%	C-:	70-72.999%	F:	less than 60