chem lab report

Report Title (i.e. Freezing Point Depression)

Introduction (2 pts)

Length: 1-2 paragraphs

Discuss the basic chemical principles behind the lab. This also includes the reasons why someone would care to test these principles. Be practical: what chemical principles are being investigated? In general terms, what do we want to know, and how are we going to find it? Include real life examples.

What method are you using ie: What is a titration? Why is it important? How is it useful? Discuss the difference between a primary and secondary standard. Discuss the qualifications of a good primary standard (do not just name them). The introduction/procedure should tell what you did. Not what “will be done.”

Correct: The boiling point was determined with the thermistor.

Incorrect: The boiling point will be determined using the thermistor.

Procedure and Observations (5 pts)

Length: 2-3 paragraphs

Include what you did and what you observed during the experiment. A good rule of thumb is that it should be detailed enough that someone can repeat the experiment from your procedure, as well as understand exactly what you saw. Do not plagiarize or copy directly from the lab manual - this section must be in your own words and cannot be bulleted or numbered points. A proper procedure will be in paragraph form.

Neglect insignificant details (turn on microlab, place on a colored background…). You must include exact volumes, molarities (the box labels are often just approximate), etc.

Observations are: color changes (color and opacity or translucence), evolution of gases, formation of precipitate (color, crystal shape, opacity), endothermic, exothermic, etc.

Correct: The reaction mixture was treated with...

Incorrect: I treated the reaction mixture with...

Incorrect: Treat the product with...

Data (3 pts)

Present your data in neatly organized and labeled tables. Graphs must have explicit and informative titles and axis labels with units. Generate your graphs in Excel or a similar program. See me, CHMY help center, or Google if you have questions on how to do this. There are Excel help documents uploaded to D2L. Tables should be appropriately titled and labeled including units. Appropriate significant figures should always be used. Include manipulated data in place of raw data when you can (do not include the mass of a beaker with and without its contents simply include the mass of the contents). If the data is not directly affecting/being included in your results/analysis/calculations it likely does not need to be included.

Correct:

Ni(DMG)2 Synthesis
Trial	Unknown Ni2+ Compound (g)	Ni(DMG)2 (g)	Experimental % Ni2+	Percent Error
1	0.210	0.267	25.8%	15.7%
2	0.205	0.242	23.9%	7.2%
3	0.198	0.254	26.1%	17.0%

Table 1: Data collected from the three trials of Ni(DMG)2 synthesis. The theoretical percent Ni2+ in nickel sulfate hexahydrate is 22.3%.

Correct:

Graph 1: Ferrozine-KMnO4 colorimetric iron quantitation assay1,2. Protein samples were analyzed prior to and after FeS cluster reconstitution. Ricca Chemical standard iron solutions were used to generate the standard curve.

Data Analysis and Calculations (6 pts)

This is the most important section of your report. Length: 4-6 paragraphs

In this section your data is manipulated and the results are calculated and explained. One equation with a sample calculation with numbers and units needs to be shown for each type of calculation in your experiment and integrated into your discussion. For example when you discuss the determined Kf of p-xylene you would include the calculation as follows. Additionally, if you show the Kf calculation for p-xylene, you do not need to show a Kf calculation for water.

(1a)

(1b)

Your results are to be interpreted for their meaning in the context of the experiment. Include chemical equations where they are discussed.

C4H8N2O2- + OH- C4H7N2O2- + H2O (2)

Walk the reader through your thought process to the conclusions you make. Use words; do not simply turn your equations into paragraph form. Ex: How do you know that KHP/NaOH moles were equal? Discuss the relationship between the endpoint and the color change of the indicator and the equivalence point. What constitutes an appropriate indicator? How would you select an appropriate indicator?

I may ask you to include the answers to questions from the lab manual or another source. These answers should be incorporated into your discussion in addition to the analysis of your data as stated in the previous paragraph. You should not type this as a question with the answer following but rather incorporate your answer as a discussion of your data. In other words, it should not be apparent to a 3rd party that you are answering a specific question.

Conclusion (4 pts)

Length: 1 healthy paragraph or 2 short.

Restate the purpose of the lab and discuss if your results were or were not what you expected and why that may be. If a theoretical value for any of your results is provided or can be found, calculate a percent error or percent yield for your results. Outline specific possible sources of error. Include only possible and reasonable errors - human error is not a valid source as it is always present. What other sources of error can you think of? Inappropriate sources of error include, “the calculations might have been done wrong”, “the correct amount wasn’t used”, “the wrong chemical was added”, etc. What’s the precision of the instruments you used? Would these affect your results? Are your results precise? Accurate? How do you know? What is the difference between the two?

REFERENCES

(1) Fish, W. W. Rapid Colorimetric Micromethod for Quantitation of Complexed Iron in Biological Samples. Methods Enzymol. 1988, 54, 357–364.

(2) Riemer, J.; Hoepken, H. H.; Czerwinska, H.; Robinson, S. R.; Dringen, R. Colorimetric Ferrozine-Based Assay for the Quantitation of Iron in Cultured Cells. Anal. Biochem. 2004, 331 (2), 370–375.

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