1.2: Introductory Details

Course Information

This laboratory course compliments the undergraduate Physical Chemistry lecture courses by providing practice in conducting laboratory work with instruments and methods relevant to physical chemistry, and by providing practice in the processing and analysis of "real" data.

The online site for this course is on Canvas. Details about the course, (announcements, grading, instructor contact, assignment submission) are available only by visiting our Canvas site. Links to this manual will be available on Canvas, although the manual "lives" on LibreTexts. The manual is a work that is constantly revised, and you will find the latest version of all experiments on the "live" LibreTexts site for this course.

I. LABORATORY SAFETY

This course requires you to understand the potential hazards associated with materials, equipment, and procedures within the chemical laboratory. This knowledge is crucial as it directly impacts the level of risk that you and fellow students may face due to your actions and those of others in the laboratory. You can help to minimize the risks posed by chemical hazards to both yourself and others by taking precautions. We strongly encourage you to consistently prioritize safety in your laboratory work. The following requirements have been established with your safety as the primary consideration:

1. A copy of the Duke Chemistry Department Safety Manual is available on the Chemistry web site. All students will read this manual prior to beginning laboratory work.
2. Safety eyewear is always required in the laboratory space.
   1. You will provide your own pair of safety eyewear to use during every lab period.
   2. If you wear prescription glasses, you should also wear safety eyewear that fits over your prescription glasses.
   3. Contact lenses may be worn in the laboratory in addition to wearing safety glasses.
3. No unauthorized work or experimentation will be allowed in the laboratory.
4. Protective shoes are required in the laboratory - no bare feet, sandals or open-toe footwear.
5. Consumable items should be kept out of the laboratory at all times. Never eat (including chewing gum), drink, or smoke in the laboratory.
6. Skin must be covered from neck to knee. Long sleeved shirt and pants should be worn. We know it can get hot in Durham, so bring extra clothes with you to lab on hot days. Clothing that are not appropriate for lab include shorts, mini-skirts, crop tops, low cut shirts, and anything that exposes large portions of your skin to chemical hazards.
7. Long hair should always be tied back while in the laboratory.
8. Safety Data Sheets (SDS) for every chemical to be used in this laboratory course are available online by googling the name of the chemical and "sds". You will read the SDS for each chemical to be used prior to arriving in lab.
9. Failure to observe safety regulations will result in substantial deduction in the lab grade and may result in ejection from the lab session. Persistent violation of safety regulations will result in permanent expulsion from the lab course.
10. Solvents and Chemicals will be disposed of properly: Departmental waste disposal procedures are described in the safety manual. However, you should always consult with an instructor before attempting to dispose of any material.
11. Precautions for individual experiments will be discussed with you by the instructional team and are described in the lab manual.

II. Preparation for Laboratory Meetings

Pre-Lab Assignment:

You should prepare for lab meetings by reading the appropriate module in this manual, and completing the specified pre-laboratory assignments. The pre-laboratory assignments are designed to prepare you to operate efficiently and safely during the experimental module. You will not be allowed to conduct experiments if the pre-lab assignment is not completed before your lab meeting. If there is an extenuating circumstance that prevents your preparation, please inform your instructors as soon as possible.

For a given experiment, you should complete the assigned reading and write out the specified pre-lab assignments. The pre-lab assignment must be submitted as a single pdf document on Canvas at least 24 hours before the scheduled lab meeting. Late pre-laboratory work will not be accepted and will receive a score of zero. Your TA will evaluate the work and return it no later than the beginning of your lab section. Your preparedness will also be evaluated by your answers to oral questions pertaining to the laboratory from the TA and other lab instructors. The pre-lab and preparation accounts for 10 points of each experiment requiring a pre-lab.

For every experimental module there is a general pre-lab assignment. It is described here:

General Pre-lab assignment:

Write a brief introduction to the experiment and the experimental plan using the following outline:

1. Experiment Introduction: In your own words, briefly describe the underlying theory and explain the principle upon which the experiment is based. Keep it concise; lengthy discussions or derivations of equations are unnecessary.
   1. Background (importance/relevance): A brief description and justification of the importance of the topic, with references to source material. What is the topic and why is it interesting and important? This is meant to "hook" the reader so they want to read about the topic.
   2. Theory: A concise paragraph or more describing the general theory for the method/technique used; this section should contain a reference to the appropriate pages of the textbook, or other source material from the literature.
   3. Goals/Purpose: Brief statement of purpose, which should indicate what is analyzed and the technique used. Limit to three to five sentences.
2. Experimental Plan: a short summary of the specific things that you would need to know in order to do the experiment without having access to your lab manual, with the understanding that you will always have a TA available to teach you how to use the instrument. The best way to approach this task is to thoroughly read the procedure for the experiment. While reading, take notes on the specifics of the work. What chemicals will you use? If you have to make solutions, what solutions do you need to make and of what concentration? How will you prepare them? What instrument will you use, and what specific instrument settings will you need to input (sometimes you will find this information in the Appendices that discuss the use of the instruments)? How many runs of each sample will you do; and over what wavelength, or temperature, etc. range? You do not need to write down how to use the instrument; we will teach you that. Bottom Line: we want you to write down only that pertinent information about samples, sample preparation, instrument and instrument parameters, numbers of runs, and other things, that you will need to know in order to do your work.

Pre-lab assignments should be typed. If you prefer to write out equations by hand, they should be neat and inserted as an image in the appropriate place. If you need advice for how to insert equations or images into your documents, please ask for help at least 48 hours before the assignment is due; an in-person (or zoom) meeting is most appropriate for this issue.

Always Wear Protective Clothing:

Please dress appropriately for a laboratory environment - this is considered an important part of preparation for the laboratory period (see also Laboratory Safety below). You must wear close-toes shoes and clothing must cover your body from your upper arms to your knees. You should also wear protective eyewear. If lab attire is not jiving with your wardrobe, please purchase a lab coat and bring it with you so that you can cover up in lab. No student should be in lab without wearing protective eyewear and appropriate protective clothing.

III. Laboratory Work and Electronic Laboratory Notbooks (ELNs)

Warning: Use cloud storage and backup

As you save your documents and develop systems of organizing your academic life, please learn to use a cloud server to automatically save and back up your work. Duke University supports cloud storage through Box and Microsoft tools. Proper use of these tools is expected. Please ask Dr. Haas if you need some instruction or recommendations for using these cloud-based tools to avoid loosing your work if/when computer hardware is lost or fails.

While we are aware that there are limited computer labs on campus, you also have access to computers also in the P-chem labs. Please plan to always complete your work 48 hours in advance so that any issues with your personal devices do not interfere with timely submission of assignments.

You will complete each experiment as a group, and there will be a dedicated instructor to answer questions. You will record observations using an electronic laboratory notebook (ELN); an example ELN template will be provided for each experimental module. The ELN will contain a written record of your group's activities during lab. Each student should collect a copy of the group data immediately after the lab meeting. Every P-chem lab computer has internet access, and you may either email data to yourself, save it using Outlook or Box, or collect it using a usb drive.

After the lab meeting, you will make the ELN your own by filling in your own work in the Background, Theory, and Purpose statements (from the pre-lab assignment). Edit these statements as necessary using the feedback from your instructor. Then, complete the questions and data analysis as specified in the Lab manual and in the ELN. Your completed ELN must be submitted for grading before the next schedule experiment (within 1 week). The pre-lab assignment accounts for 10 points, and the ELN accounts for 30 points for each experimental module.

Using the electronic laboratory notebook (ELN) template

Note: before beginning any electronic laboratory notebook entry, select Highlight Changes from the Track Changes option under the Tools menu in Microsoft Word. This way if you accidentally erase good data it can be retrieved afterwards. SAVE OFTEN when working outside the safety net of cloud-based autosave and backup!

There are three sections to each ELN: The "Observations and Data" section should be edited during lab while your group is working together. The other sections must be written by you and should be your own work.

Pre-Lab section:

(Your own work) This is where you will copy/paste your own pre-lab work.

Observations and Data:

(Group data collection) Record all observations and primary data as a group. This section should not evaluate the data/observations in any way. If data are being collected by hand it should be in clear, easy to read format (tables work well). Data collected at a station away from your computer may be written on paper and immediately entered into the ELN file. For data that are collected by a computer interface to your equipment, note the specific run and the name of the data file in case you have to retrieve the file later! Take screen shots as necessary to capture important data to insert into the ELN. Write observations for each run, including "bad" or aborted runs, in a narrative style and state where the actual data file can be found (including filename) when needed.

Post-Lab work:

(your own work)

Calculations of results and uncertainties: Unless otherwise instructed all calculations of results and uncertainties should be included as part of the laboratory notebook. In this course doing so will require the typing of a lot of mathematics. Please remember that you always have the option of writing your calculations out neatly on plain paper and scanning it to make a digital image that can be incorporated into an electronic notebook entry. See instructions provided earlier in this section to learn how to do that.

Discussion of results: In this section you truly “think in the notebook”. Reflect on what you have done. Write this section in your own words after the observations are completed. Include charts, graphs (see below), tables or rearranged data and your rambling thoughts. Remember this is not a formal report. You want to be neat and complete, not necessarily a literary star. This section need not be long, but it should contain all pertinent information.

Graphs: Often you will generate graphs from your primary data files. They must be represented in this section of the laboratory notebook. It is not difficult to include digital copies of graphs within the electronic laboratory notebook, but you should remember that such images can easily make the file sizes large and thus difficult to work with. Below is a procedure that will work to include copies of your graphs in the notebook while minimizing the overall size of the resulting file. A reliable way to capture graphs/plots to insert into your lab notebook is to use WinSnap for PC (or screenshot on Mac). Each lab computer has WinSnap installed. You can take a screen shot by pressing SHIFT + COMMAND + S on the keyboard. This will allow you to select a region for capture and the image will be saved to the clipboard. Press CONTROL + V to paste. You can also open the WinSnap program from the desktop shortcut instead of using keyboard shortcuts. (SAVE OFTEN!)

Here are a few more pointers for lab reports

BE BRIEF AND CONCISE! This is one of the most difficult aspects of good writing to master. Read over your first draft and be ruthless in chopping out superfluous words, phrases, or sentences. Learn to be economical in expressing yourself. The total length of the lab report should be less than 15 pages (but please don't aim for 15! That's really long!). Short is sweet!

WATCH YOUR GRAMMAR! You may be a brilliant scientist in the lab, but your credibility will be diminished if you can't communicate your results. Science has two parts: doing novel and reproducible experiments, and being able to tell other people what you did!

WATCH YOUR SPELLING! You will not be marked down for the occasional typographical error, but a report full of spelling errors will be penalized. Take the time to proofread the draft of your text at least once.

Some particular comments on writing a scientific report:

• All tables should be numbered and titled. The table headings should include the units.
• All figures should be numbered and titled. If the figure is a graph, the axes should be clearly labeled, including the units. If more than one set of data is included on the graph, use different symbols and a legend to identify them.
• Tables and figures should be presented on different pages, not included with the text. More than one table or figure can be placed on a page, however. Be sure to refer to any table or figure in the text, e.g. "The current and potential values from which E and n were calculated are reported in Table 2, and plotted in Figure 3."
• All equations presented in the text should be numbered and all symbols defined, as shown in the example below:

"The diffusion-limited current, \(i_d\), is related to the bulk analyte concentration, \(c_a\), by the following expression:

\[ \; \; i_d = nFSD_a^{1/2}c_a/(\pi \Delta t)^{1/2} \]

where n is the number of electrons transferred, F is the Faraday constant, S is the electrode area, D_a is the diffusion coefficient of the analyte ion, and t is the time during which the current is sampled."

Remember, the all-important criteria in determining the quality of the report are that it be clear, concise, and provide enough information so that anyone else with your level of experience could repeat your work without consulting you.

Students without experience in writing reports are sometimes concerned about the length of the report and the time they take to write it. The first report may take longer, but with experience you will find that a good report can be written in a few hours. The most important aspect is that it presents the data and their analysis clearly and concisely. This can usually be done in 4 or 5 pages. If you have access to a word processor, you should use it to prepare reports. Editing is then very easy, and a neat copy is easily produced.

IV. Laboratory Etiquette (Work well with your team of instructors)

There is a team of instructors to help you, including the course director (a Ph.D. chemist) and several Teaching Assistants (TA's) who are graduate students earning their PhD's in chemistry. One or more TA's will be in the lab with you each day, and one of them will be dedicated to helping you and at least one of your lab-mates to run a given experiment. That dedicated TA will be present during the laboratory to assist you, offer tips, and advice.

Use lab time to work on ELNs and writing assignments: You should consult with your TA about a given ELN before completing it - that TA will be grading your work and thus can advise you best on what you should focus. This consultation should happen during scheduled lab time - do not leave lab early just because you have finished the experiment and cleaned up. Use lab time wisely to work on your data and consult with your TA so they can help you during your time with them. The TA can show you the important points to be emphasized in evaluating your data and will discuss the grading scheme.

Email policy: We want you to do well, and we want to help you. So please ask for help well before your assignment is due. If you have questions that come up outside of lab meetings, you may email your TA at least 2 business days before your lab report is due to ask questions about an assignment. That means that if your assignment is due on Monday around 1 pm, it is wise to request help before Thursday morning (and Wednesday is better). Your instructors will not respond to you over the weekend, and may not be available. Please be polite in your email correspondences. Please also recognize that questions about chemistry are often difficult to answer in an email, and a meeting may be much more effective. Please take advantage of lab time and office hours for this reason.

"Open Lab" Hours: Ope Lab hours are times when you may drop by - these are like office hours, but we'll be in the lab or classroom. Open lab hours are posted on the course syllabus.

Office Hours: See "Open Lab" hours. We expect you to take full advantage of scheduled lab times and the open office hours to get the help you need. However, if you have done so and still need additional support, you can access your instructors through office hours. The office hours schedule with your team of instructors is posted in the course syllabus. Some instructors hold office hours only upon request, while others prefer a regularly scheduled meeting time.

A list of TAs with their experiment assignments and office hours is posted on the course syllabus.