Chemistry Formal Lab Report Assignment

Chemistry Formal Lab Report Assignment

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Instructions:

Chemistry Formal Lab Report Assignment

Description

After reviewing concepts such as light, energy, Beer’s Law, complementary colors, spectrophotometry, standard solution preparation, dilution calculations, calibration curves, and other related techniques, now it is time to validate understanding of these laboratory skills and calculation readiness through an experiment measuring the concentration of an artificial dye in a common sports drink. The artificial dye is called Red #40. Food additives, such as artificial colors and flavors, are common in American food. We often debate whether these substances are safe to consume in the quantities that we do. Ultimately, the U.S. Food and Drug Administration (FDA) has approved various artificial colors and flavors for use in a variety of products, from foods, cosmetics, medication, etc. The technique being used isspectrophotometry, which we’ve learned uses light energy to relate to concentration of chemical species, as long as the chemical species absorbs the light. The purpose of this lab experiment is to determine the concentration [in units of molarity] of Red #40 in a common sports drink using spectrophotometry.

Part of the experiment requires calculating concentrations of standard solutions and generating a calibration curve. These standard solutions are prepared via a technique called serial dilution. A small amount of a stock solution is dispensed in separate volumetric flasks and diluted with water. The concentration of each flask’s solution can be calculated using the dilution equation: M1V1 = M2V2. Take proper care to identify each of the variables in this equation correctly!

Now let’s get to the fun part of what to expect when watching this lab experiment unfold via video.

Instructions:

Please review class notes on Light, Beer’s Law, Spectrophotometry, standard solutions, the use of M1V1 = M2V2, graphing a calibration curve & using it for calculations of unknowns, the two JoVE videos related to these topics, and the theory tab in the Eutrophication Labster if you need a refresher of knowledge before viewing this lab experiment. THEN, watch the experiment video linked here and in Sakai. Have your lab notebook. Note not only the data necessary to answer the purpose of the lab but also the proper techniques that the experimenter is using/explaining in the video. To help with obtaining data, you can pause or replay the video at any time. Once you have collected the necessary data, complete the calculations, and then type the formal lab report.

At the beginning of the video, you will see a bottle of stock Red #40 solution, five of the 50.00 mL volumetric flasks for standard solution prep, a blue variable volume pipettor w/a plastic tip, and a bottle of sports drink. What to look for and record when watching the video: concentration of Red #40 stock solution, volume of stock solution dispensed into each of the 50.00 mL volumetric flasks, and the absorbance reading for each standard solution. Also make sure to record volume of sports drink dispensed into a 10.00 mL volumetric flask and the absorbance of the diluted sports drink sample. See the Calculations part on the next page.

Summary of Experimental Procedure:

A stock solution of known concentration of Red #40 was prepared in the lab. A set of five 50.00 mL volumetric flasks and one 10.00 mL volumetric flask were washed and placed on the lab bench. A blue variable volume pipet w/a plastic tip and a black grease pencil (for writing on glassware) were obtained. A bottle of sports drink was purchased from the store.

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A set of standard solutions were prepared by dispensing a known volume of stock Red #40 solution into each of the 50.00 mL volumetric flasks and diluting the flasks with water. The flasks were inverted to homogenize the solutions. Then the SpectroVis spectrophotometer was prepared and calibrated. Each standard solution was analyzed in the spectrophotometer and its absorbance value recorded. This concludes the data necessary for generating a calibration curve. Then the sports drink was diluted, as was too concentrated to analyze directly from the bottle. A dilution was prepared by pipetting a known amount of the sports drink into a 10.00 mL volumetric flask, diluting the flask with water, and inverting the flask to homogenize the solution. Then the diluted sports drink sample was analyzed in the SpectroVis spectrophotometer and absorbance value recorded.

Calculations:

With the necessary data written down, complete the proper calculations to generate the calibration curve with any graphing software [use all appropriate techniques learned in the graphing assignment]. It is a good idea to show calculations of M1V1 = M2V2 in the lab notebook. Pay attention to significant figures. After obtaining the line of best fit, y = mx + b, from the calibration curve, use it with the absorbance of the diluted sports drink to calculate the dilute concentration of Red #40 dye. Then take into account the dilution to obtain the ‘true’ or undiluted concentration of Red #40 in the sports drink.

Now that the undiluted concentration of Red #40 in the sports drink is known, let’s reflect on the maximum ingestible limit of the dye. Red #40 has an acute oral LD50 of roughly 5000 mg dye/1 kg body weight. This means if a person had a mass of 1 kg, ingesting 5000 mg of Red #40 will result in that person having a 50% chance of demise. Determine the amount of dye a 70 kg person would need to eat to reach the LD50. How many moles of dye would that be? The molar mass of Red #40 is 496.42 g/mol. Using the calculated undiluted concentration of Red #40 dye in the sports drink, how many of liters of sports drink would it take to reach this LD50?

Formal Lab Report:

Include data table, all results, and all calculations in your formal lab report. The instructions for writing the formal lab report can be found in Sakai under Resources. These are the same instructions given for the midterm formal lab report. Submit a typed formal lab report in Sakai under Assignments tab.

Cite this document as the lab manual when writing the formal lab report, especially in experimental details section when writing the sentence that no procedural changes were present since the lab is done online and that this procedure was followed.

Here is the lab handout/manual citation:
Sports Drink Analysis via Spectrophotometry, Chem 111 Lab Manual, Fall 2020, pgs. 1-2.

Also cite the experiment video:
“Sports Drink Analysis via Spectrophotometry”, Panopto, Fall 2020.

While working in the lab, lab notebooks are used to record data, results, observations, calculations, and thoughts. Eventually there comes a time when this data should be shared with the broader scientific community. This can be done in the form of oral or poster presentations, but the main method of sharing data is through scientific journals. There are hundreds of different journals available, each specializing in a particular area or topic. A glance at the American Chemical Society’s journal page, https://pubs.acs.org/ shows the wide scope of chemical research being published. These publications are not limited to chemistry, there are journals for physics, biology, medicine, health fields, humanities, and any other field you can possibly imagine.

Writing formal publications and reports is a valuable and required skill for anyone in a scientific field. Those not in the scientific field also benefit from understanding how scientific information is presented. The semester, there will be two formal reports written. After viewing two recorded labs, a formal report will be written as if you are performing the experiment. The

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There are no page requirements, it should be long enough to contain all of the required information. Don’t add unneeded or extra information just to make it longer.

Double spaced

12 pt font

Page #s in bottom right hand corner of page

Use a serif font such as Times New Roman or Cambria for the printed copy.

1 inch margins

Use superscripts and subscripts where appropriate for chemical formulae.

Each student will write their own formal lab report.

Graphs (if applicable) should be made in a graphing program.

FORMATTING FIGURES AND GRAPHS

Figures are sequenced in order of appearance (Figure 1, Figure 2, etc.). If a graph is to be included, treat it like a figure. Under each figure, the figure number should be in bold, followed by a brief description of the figure. Each figure should be specifically referenced in a sentence somewhere nearby the figure. When specific figures are referenced, they should be capitalized. See Figure 1 below and checkout other figures in this guide for examples.

first formal report is due during week 8, October 12
KHP titration and video given in week 7. The second formal report is due during week 12, November 9th – 13th and will be based on a UV-Vis experiment given in week 11.

FORMATTING AND ASSIGNMENT GUIDELINES

Page 1 of 9

– October 16

. This will be based on a

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Figure 1. The lakeside view of Loyola University Chicago.

SECTIONS IN A FORMAL REPORT

Every journal has specific requirements for how to organize information and data. A guideline for each section required in the Chem 111 report will follow as well as an example of how this section correlates to a section in an actual journal article. A Chem 111 report should have the following sections:

1. Title
2. Introduction 3. Experimental 4. Results
5. Discussion
6. Conclusion
7. References

In the resource section on Sakai, there should be a folder with Formal Lab Report information. A copy of the referenced journal articles is uploaded in there.

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1. TITLE

A title serves to accurately display the topic of the paper. The title alone should be a good indicator of the specifics of the paper, although an abstract often times helps to inform potential readers of the paper what to expect. Figure 1 below shows a title of a recent journal

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Your name, clearly indicate this paper belongs to you!

Date your report will be submitted

Section number

TA Name

Chemistry Formal Lab Report Assignment

RUBRIC
Excellent Quality 95-100%	Introduction 45-41 points The background and significance of the problem and a clear statement of the research purpose is provided. The search history is mentioned.		Literature Support 91-84  points The background and significance of the problem and a clear statement of the research purpose is provided. The search history is mentioned.			Methodology 58-53 points Content is well-organized with headings for each slide and bulleted lists to group related material as needed. Use of font, color, graphics, effects, etc. to enhance readability and presentation content is excellent. Length requirements of 10 slides/pages or less is met.
Average Score 50-85%	40-38 points More depth/detail for the background and significance is needed, or the research detail is not clear. No search history information is provided.		83-76  points Review of relevant theoretical literature is evident, but there is little integration of studies into concepts related to problem. Review is partially focused and organized. Supporting and opposing research are included. Summary of information presented is included. Conclusion may not contain a biblical integration.			52-49  points Content is somewhat organized, but no structure is apparent. The use of font, color, graphics, effects, etc. is occasionally detracting to the presentation content. Length requirements may not be met.
Poor Quality 0-45%	37-1 points The background and/or significance are missing. No search history information is provided.		75-1 points Review of relevant theoretical literature is evident, but there is no integration of studies into concepts related to problem. Review is partially focused and organized. Supporting and opposing research are not included in the summary of information presented. Conclusion does not contain a biblical integration.			48-1 points There is no clear or logical organizational structure. No logical sequence is apparent. The use of font, color, graphics, effects etc. is often detracting to the presentation content. Length requirements may not be met
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