ORGANIC CHEMISTRY LAB REPORT FORMAT

There is a standardized lab report format that you will need to follow. There is a significant amount of pre-lab work that needs to be completed before the lab starts. The pre-lab is hand-written in your lab notebook and should contain the following labeled sections:

PRE-LAB WORK:

• TITLE - The full name of the experiment

• PURPOSE: A brief description of what you will be doing in the lab

• CHEMICAL EQUATION: Only include this if you are actually performing a chemical reaction (A + B → C + D). Write the balanced overall chemical equation for the reaction. Draw the chemical structures and include the chemical formulas and names.

• PROCEDURE: Point form (bullet) summary of the text procedure. This can be simplified as you will record a detailed, step-by-step procedure during the experimental phase.

• HAZARDS: List the hazards and physical properties for ALL of the chemicals that you will come in contact with during the lab (including the products formed). You must be aware of the safety hazards so that you can minimize your exposure to harmful chemicals. This information can be found on any MSDS (material safety data sheets). A good site for MSDS is: http://hazard.com/msds/, or you can just do a web search for the chemical name and select any MSDS link. The MSDS sheets include a lot of information, but you should just list the information from the following sections:

Section #1: Product Identification - chemical name, chemical formula, CAS No, Molecular Weight

Section #3: Hazard Identification - A few key words such as flammable, corrosive, carcinogen, etc. Or you can just list the NFPA rating scale (health - fire - reactivity). These criteria are rated on a scale of 0-4 with 4 being the most dangerous.

Section #9: Physical and Chemical Properties - appearance, odor, density (specific gravity), boiling point, and melting point.

Experimental Phase: The DATA section must be detailed and contain all the necessary information to be able to repeat the experiment using the notebook as the only available source of information. You cannot refer to the textbook, or another document, in lieu of a competed notebook. Remember, for any scientific experiment to be valid, it must be repeatable for the same results. The more information listed in this section will make it easier to duplicate the results later.

DATA & OBSERVATIONS: Recorded in the lab notebook.

• Record ALL the experimental steps. It is important to state what you actually did to yield the results. Often the pre-lab procedures do not provide enough information, or changes are made when you are in the lab.

• Include detailed equipment diagrams as necessary so you can refer back if the same technique is used in another lab experiment.

• For any number recorded as a measurement, you must have the units assigned and clearly identify what is being measured. Just listing a number by itself doesn't mean anything!

DATA & OBSERVATIONS Cont.

• Include any observations, such as color changes, odors emitted, phase changes, etc.

• When you make a product, various techniques may be used to test the purity of the product. This data must all be recorded as follows:

Melting Point (for solids) - 3 melting point trials (with a melting range for each trial)

Boiling Point (for liquids) - 1 trial only unless the result differs from the literature value by more than 5oC.

Spectroscopy methods - You'll be introduced to various spectroscopy methods (IR, GC/MS, NMR) during your organic chemistry courses. If you do perform any of these methods, you'll need to analyze each spectrum and turn it in with your lab report. For example, if you run an IR (Infrared) spectrum on your sample, you will need to identify all of the principal peaks and list them in the data section.

CALCULATIONS: Recorded in the lab notebook.

All mathematical calculations are written in this section. This enables another scientist to determine whether there was a possible math error. Common calculations that you will have to perform include:

Melting Point Determination

3 trials performed with a melting point range for each trial. Calculate the average of each trial and then find the average of those values to determine the final observed melting point.

% Error (for melting point, boiling point, density, etc.)

% error = ¦literature value - observed value¦ x 100
literature value

% Yield (for any product made)

1. Balance the overall chemical equation
2. Determine the moles of limiting reactant and then moles of product
3. Convert moles of product to mass of product - this is the theoretical mass
4. Calculate the % yield

% yield = Actual mass x 100
Theoretical mass

Lab Report

The lab report is a summary document written to inform the reader about the overall accomplishments of the experiment. The lab report must be typed and include the following sections:

Title of Experiment

Purpose

Chemical Reactions

Discussion - Provide a detailed summary of the chemistry and your experimental results in paragraph format. This is where you'll interpret your data and calculations and describe the outcome of your experiment. You should clearly state your findings and provide enough information so that someone could just read your discussion and know what your results were. Unless appropriate you do not need to include the raw data or calculations, but you should include the final values for % error, % yield and any other significant calculations performed. Discuss the sources of error and ways to improve the results. Include any spectroscopy results and how they compare to the literature spectrographs found in the lab text, when applicable. Avoid the use of I or My statements and use the passive tense. Include any literature references when necessary.

Conclusion - A brief statement of the experiment and if it was successful or unsuccessful. Did you accomplish what you set out to do?

Post-Lab Questions - Answer all assigned post-lab questions.

The lab report is due at the beginning of the following lab meeting. Attach all the pages used in your lab notebook (start of pre-lab through calculations) and any spectra that were analyzed (IR, NMR, GC/MS). Staple the typed report to the front and make sure your name is on the report.

Isolation of the Active Ingredient in an Analgesic Drug

Extra handout - This provides more details about your experiment and information that will differ from the lab manual.

Procedure:

1. Use aspirin or acetaminophen. Ibuprofen will not be assigned.

2. Use 10 mL beaker to bring some methanol back to your station.

3. Omit calibrated pipet. A full bulb depression is approximately 2 mL, or use graduated markings on vial.

4. Doing the extraction 3x instead of 2 will produce higher yield. This is the part when you add 2 mL of methanol, shake, settle, and transfer liquid to centrifuge tube. Add all three portions to the same centrifuge tube for the next step.

5. Omit filter-tip pipet. Use regular pipet.

6. Make sure centrifuge is balanced before running. If you are unsure how to do this, please ask your instructor.

7. For the column chromatography simply follow the diagram on page 53. You only need a small piece of cotton that covers the area shown in the diagram and about 2 cm of alumina. Once you condition the column with a 2 mL portion of methanol, do not allow the liquid to run under the top of the alumina. Add your product before it drains to under the top part of the alumina. You can catch the initial methanol in a beaker to discard, but once you add the product catch the remaining liquid in a 5 mL conical vial for the next step.

8. For evaporation of the solvent, use a 50 mL beaker for the water bath. Make sure the level of the water is higher than the liquid in the vial but not higher than the actual vial. If you use a beaker that is too large or fill it too high your vial can tip over and your product will be lost.

9. Ensure that the vial cools to room temperature before putting it in an ice bath. If you move it directly from the heat into the ice bath this can cause the glassware to crack or shatter.

10. The Hirsch funnel diagram is not found in our lab manual. Your instructor will demonstrate the setup on a side bench. Make sure you have it connected to a vacuum trap so that any particles that come through the funnel will get caught in the trap instead of being sucked directly into the vacuum. Tubing is heavy so ensure that the flask and all parts are secure before attaching it.

11. Crystals are dry when you can stick the microspatula into them and none of the product sticks to it.

12. Take melting point the same way as practiced in the previous lab. Use the average of the averages as your actual value to calculate your percent error.

13. Omit handing in your product. Discard leftover in waste jug when finished taking weight and melting point.

14. Include in your post-lab discussion the % error, % yield, and sources of error.

15. Post-lab questions 1-6.

1. Why was the percentage recovery less than 100%? Give several reasons.

2. Why was the tablet crushed?

3. What was the purpose of the centrifugation step?

4. What was the purpose of the alumina column?

5. If 185 mg of acetaminophen were obtained from a tablet containing 350 mg of acetaminophen, what would be the weight percentage recovery?

6. A student who was isolating aspirin stopped the experiment after the filtration step with alumina. One week later, the methanol was evaporated and the experiment was completed. The melting point of the aspirin was found to be 110-115°C. Explain why the melting point was low and why the melting range was so wide.

Attachment:- Images.pdf