Separation and Analysis of a Solid Phase Mixture Lab Handout

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- 1- Separation and Analysis of a Solid Phase Mixture Purpose: To introduce liquid-liquid extraction as a separation technique and to use infrared (IR) and 13 C NMR spectroscopy as tools to evaluate the success of the separation. Theory: Extraction Extraction is the process of separating components of a mixture, usually based on differing solubility. When you make coffee you are performing a solid-liquid extraction. In the laboratory, a more common form of extraction is a liquid-liquid extraction. In this form of extraction, compounds of interest dissolved in a liquid are selectively removed using a second liquid which is insoluble in the first. Addition of an insoluble liquid creates a two- layered system. For this technique to work, one of the compounds initially dissolved in the first layer must be much more soluble in the new layer. A special piece of glassware, known as a separatory funnel, is used for performing a liquid-liquid extraction. In this experiment you will separate caffeine and ibuprofen from an analgesic mixture. Analgesics Analgesics are a class of pain-relieving compounds. Examples include acetaminophen, acetylsalicylic acid, ibuprofen and caffeine. In over-the-counter (OTC) pharmaceuticals these compounds may be present individually or as a mixture. For example, Aspirin contains only acetylsalicylic acid while Anacin contains both acetylsalicylic acid and caffeine. Research has shown that, although caffeine and ibuprofen work independently as analgesics, they are more effective when taken in combination for treatment of tension headaches. Currently no OTC medication in Canada contains both ibuprofen and caffeine because a safety alert issued by the USDA in 2009 warned of an increased risk of internal bleeding for this combination of analgesics. The structures of ibuprofen and caffeine are shown in figure 1. Caffeine is a weak base and ibuprofen is a weak acid. Both compounds dissolve in aqueous ammonia. In doing so, ibuprofen loses a proton and forms an ammonium salt; caffeine retains its molecular structure. The caffeine can therefore be extracted into an organic solvent like dichloromethane and the ibuprofen will remain in the aqueous layer. Adding acid to the aqueous layer after the caffeine is removed will re-protonate the ibuprofen causing it to precipitate. Filtration can then be used to remove the ibuprofen from the aqueous layer. Each component is now contained within separate fractions which can be dried and evaluated for purity using spectroscopic techniques. N N N N O CH 3 CH 3 O CH 3 CH 3 HO O CH 3 H 3 C caffeine ibuprofen MW = 194.19 g/mol MW = 206.28 g/mol Figure 1: The Structures of Caffeine and Ibuprofen

- 2- Infrared Spectroscopy Remember the electromagnetic spectrum? Each region of this spectrum is characterized by the wavelength, frequency and energy of the emitted radiation. When a molecule absorbs radiation it is affected in some way. Each range of wavelengths (or frequencies) of absorbed is associated with a characteristic type of excitation. For example, infrared wavelengths from 2.5 to 25 µm, cause the bonds in molecules to stretch or bend. Infrared spectroscopy is most useful in determining the presence (or absence) of functional groups. Each functional group typically appears in a specific region of an IR spectrum (Table 1). This information allows synthetic chemists to follow the progress of a reaction or to confirm they have synthesized a specific type of compound. Computer- based resources to help you learn infrared spectroscopy include the visualization tools at http://www.kcvs.ca/. Table 1: Correlation of Infrared Absorption and Selected Functional Groups Type of Absorption Wavenumber (cm -1 ) Intensity Functional Group O-H stretch 3400-3640 strong,broad alcohol 2500-3300 strong, very broad carboxylic acid N-H stretch 3300-3500 medium 2° amine 3250-3300 medium 2° amide -NH 2 stretch 3250-3450 medium 1° amine 3340-3360 and 3170-3190 strong 1° amide C-H stretch 3300 strong sp C-H of alkyne 3030 medium aromatic 3020-3100 medium sp 2 C-H of alkene 2850-2960 medium - strong sp 3 C-H of alkane 2750-2850 weak - medium, w-shape O=C-H of aldehyde C=O stretch 1670-1780 strong, sharp carbonyl 1730-1750 ester 1720-1740 aldehyde 1705-1725 ketone 1700-1725 carboxylic acid 1640-1700 amide C=C stretch 1650-1670 weak - medium, sharp alkene 1600, 1500, 1450 strong, sharp aromatic C=N stretch 1640-1670 medium, sharp imine N-H bend 1500-1650 medium - strong, sharp amine and amide C-N stretch 1030, 1230 medium amine N-H or NH 2 wag 750-850 strong, broad amine, amide Note: For conjugated C=C with C=O, the observed C=O absortion will be < ~ 30 cm -1

- 3- 13 C Nuclear Magnetic Resonance Spectroscopy NMR spectra are generated when molecules absorb radio frequencies causing nuclei in atoms to flip spin states and provides the chemist with insight into the carbon-hydrogen framework of an organic molecule. NMR is possible due to the magnetic properties of certain nuclei. You might expect that all nuclei of the same type would absorb the same frequency of radiation. If this were true, NMR would not be very useful for determining structure. In fact, the energy for each nucleus varies with its environment. Electrons that surround the nucleus shield it from the applied magnetic field. Therefore, upon exposure a magnetic field, nuclei with different structural environments will resonate at different frequencies. NMR spectra are displayed on charts that show the applied field strength increasing from left to right. Generally the nuclei of a carbon atom attached to a more electronegative element will appear at a larger chemical shift value (lower field). A nucleus with more electronic shielding resonates at a higher frequency and appears father to the right in the spectrum. The position on the chart at which a nucleus absorbs is called its chemical shift . Figure 2 shows some typical chemical shifts. Chemical shifts are standardized, in units of ppm (parts per million) so that experimental values can be readily compared to literature values. Note that lower field corresponds to a higher ppm value. At its simplest, 13 C NMR makes it possible to count the number of different (non- equivalent) carbon atoms in a molecule of unknown structure. Each non-equivalent carbon produces a single peak in the 13 C NMR spectrum. In the simple case of methane, CH 4 , the 13 C NMR would show only one signal. Figure 2: Typical 13 C NMR Chemical Shifts 50 0 Saturated carbon (sp 3 ) no electronegative elements Saturated carbon (sp 3 ) electronegativity effects Alkyne carbon Unsaturated carbon (sp 2 ) Aromatic ring carbons Carbonyl Groups Acids, Esters, Amides, Anhydrides Aldehydes, Ketones 0 R 2 C=O (185 - 220 ppm) R-CH 3 (8 - 30 ppm) 200 150 100 50 C≡C (65 - 90 ppm) R 2 C=CR 2 (100 - 150 ppm) (110 - 175 ppm) R 2 C=O (155 - 185 ppm) 200 150 100 R 3 C-Br (25 - 65 ppm) R-CH 2 -R (15 - 55 ppm) RCH 3 R 3 CH (20 - 60 ppm) R 3 C-O- (40 - 80 ppm) R 3 C-Cl (35 - 80 ppm)

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- 4- Advance Study Assignment: Before coming to lab for week one of this experiment you must complete a Moodle quiz which focuses on interpreting hazards you might encounter while performing this experiment. You should also read the documents on Weighing Procedures and Using a Separatory Funnel posted on Moodle. Consider watching the video at https://www.youtube.com/watch?v=8bZl7mcG0Ew to familiarise yourself with the technique you will use in lab. Safety: Safety goggles are required at all times while performing this experiment. Wash your hands immediately if you spill something on them. Notify your instructor and fellow students if you accidentally spill anything. Your instructor will assist you in neutralizing and cleaning up the spill. Reagent hazards for this experiment are summarized in Table 2. Table 2: Summary of Reagent Hazards Reagent Name Molecular Formula WHMIS 2015 Pictograms Other Hazard Notes Ammonium hydroxide (1 M) NH 4 OH Causes severe burns and eye damage. May cause respiratory irritation. Use with adequate ventilation Caffeine C 8 H 10 N 4 O 2 Toxic if swallowed. Irritant Dichloromethane CH 2 Cl 2 Suspect carcinogen (1B) Respiratory hazard; may cause dizziness. Irritant. Use a fume hood Hydrochloric Acid (6 M) HCl Causes severe skin burns. Releases corrosive vapour. Use a fume hood. Ibuprofen C 13 H 18 O 2 Oral toxicity category 4. Teratogen. Chloroform CHCl 3 Exposure can cause nausea or dermatitis. Carcinogen and reproductive toxicity (category 2). Use a fume hood. Scenario: A pharmaceutical company must ensure both the purity and the dosage of the active ingredients in its products. The samples contain both ibuprofen and caffeine in unknown composition. Your job is to separate these compounds from each other and to determine the relative amounts of each component in the sample. You will also use IR and interpret 13 C NMR analysis to evaluate how effective your separation was. Materials and Equipment: Week 1 unknown sample 1 mol/L NH 4 OH (aq) 125 mL Separatory funnel dichloromethane 6 mol/L HCl (aq) Whatman #2 filter paper (12.5 cm) retort stand (in cupboard U1) 2 cm ring clamp NaHCO 3(s)

- 5- Procedure: Adapted from Szalay, Paul S. J. Chem. Educ. 2008 , 85 , 285-287. You may work with a partner to complete this experiment but must ensure full participation in learning all techniques. Your instructor will demonstrate use of a separatory funnel, quantitative transfer and gravity filtration. -Week 1- There is no one optimized procedure that everyone can use due to the variety of mixture compositions being separated. Make use of visual clues and inductive reasoning to determine appropriate quantities of reagents. Record (in ink) what you observe and what you measure on your observation sheet as you work through the procedure. Preparing the Sample and Apparatus 1. Obtain a vial containing a previously mixed sample of caffeine and ibuprofen. Record the sample number and describe what the sample looks like. 2. Use proper weighing techniques to weigh the vial and its contents. 3. Weigh a 100 mL beaker, tare it. Transfer the sample into the beaker. Record the mass. 4. Reweigh the vial and sample residue. The mass of your sample is the difference between this mass and the one measured in step 2. It is important that you use the same balance for measuring both masses. This analytical technique is called “weighing by difference”. 5. Add 1 mol/L NH 4 OH (aq) to the beaker until the sample just dissolves; stirring will help. 6. Assemble a separatory funnel and check it for leaks using distilled water. 7. Once you’ve confirmed your funnel is leak free, empty the water, close the stopcock and move it to a fume hood along with a retort stand and ring clamp. 8. Transfer the dissolved sample from step 4 into the separatory funnel. Rinse the beaker with a small volume (2 - 3 mL) of distilled water and add this to the separatory funnel. Repeat with two or three more small rinses. This technique is called a “quantitative transfer” and helps ensure that the entire sample is now in the separatory funnel. 9. Label a 125 mL Erlenmeyer flask with your name(s), drawer number(s), sample number, and “caffeine in dichloromethane”. Weigh the flask. Extracting the Caffeine 10. Using proper technique and three separate 10 mL portions of dichloromethane, extract the caffeine from the unknown solution. a. Add about 10 mL of dichloromethane to the funnel. Dichloromethane (DCM) has a density of 1.3 g/cm 3 which is larger than that of dilute aqueous ammonia which has a density of about 1.0 g/cm 3 so it will form the bottom layer . b. Insert and tighten the stopper and then take the separatory funnel out of the ring. Grasp it firmly in your dominant hand while holding the stopper in place. c. Invert the funnel slowly, pointing it towards the back of the fume hood, and open the stopcock to vent any built-up pressure. This is called venting . d. Close the stopcock and shake the funnel gently. Vent regularly. Continue for 2 – 3 minutes. e. Place the separatory funnel back in the ring and allow the layers to separate. f. Drain the bottom layer containing dichloromethane and caffeine into the previously weighed and labeled Erlenmeyer flask. g. Repeat steps a. through f. two more times. 11. Leave the Erlenmeyer in the fume hood to allow the solvent to evaporate.

- 6- Separating the Ibuprofen 12. Pour the solution from the separatory funnel into a clean beaker. Rinse with a few small portions of distilled water to quantitatively transfer the sample. 13. At your bench, use a Beral pipette to add 6 mol/L HCl (aq) drop-wise to the solution in the beaker. Do not swirl. Continue slowly adding acid until you do not observe any more precipitate forming. 14. Weigh and then fold a 12.5 cm disc of Whatman #2 filter paper. Fold the paper in half and then into quarters. Open with three layers on one side and one on the other and fit the paper into your funnel. 15. Wet the paper with a few drops of water and then collect the precipitate using gravity filtration as demonstrated by your instructor. 16. Rinse the beaker with distilled water and filter that solution too. The filtered solution is called the filtrate . 17. Confirm that all the ibuprofen has precipitated by adding a drop of 6 mol/L HCl (aq) to the filtrate. If no additional precipitate forms you have added enough acid. If you observe more solid forming, you’ll need to add more acid and re-filter. 18. Use a wash bottle to squirt distilled water over all the precipitate in the funnel and allow this solution to filter through. Repeat if time allows. 19. Label and weigh a large watch glass. Put the filter paper with the precipitate onto the watch glass and place it in your drawer. Clean Up The collected filtrate must be neutralized. Pour the filtrate into the large beaker containing sodium bicarbonate and water which is near the sink by the window. Swirl until bubbling stops. If there is still solid sodium bicarbonate in the beaker, leave the beaker for others to use. If not, add more NaHCO 3(s) . Once everyone is done the experiment your instructor will confirm a pH of 6 – 8 before pouring the neutralized solution down the drain with water. Wash your glassware with soap and water and return any common glassware and equipment to where you found it. Wash your bench top and the fume hood space you used. Wash your hands. Submit a copy of your observation sheet before leaving the laboratory. (3 marks)

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- 7- -Week 2- To maximize efficiency, you may be divided into two large groups. One group will initially work with KCVS’s computer-based learning tools and/or Spartan and then collect IR spectra for their compounds. The other group will do the reverse. You can use any campus computer lab to complete the Spartan component. Materials and Equipment: KBr disc and sample holder Kimwipes chloroform (dry) size 1 corks dichloromethane Pasteur (glass) pipettes Bruker Alpha FTIR Spectrometer Halogenated Organic waste container Procedure: Part A: Computational Chemistry Using the Computer Tutorials – KCVS If you need to review the IR analysis tools learned in lecture, log in to the network and access http://www.kcvs.ca/site/projects/chemistry.html . Open the Functional Groups, IR Spectra and Molecular Vibrations applet. Look at the IR spectra and associated molecular vibrations of various functional groups giving most attention to the functional groups that allow you to differentiate between ibuprofen and caffeine. Using Spartan Computational chemistry is a tool of increasing importance in chemistry. You will use Spartan Student v.8 which will assist you in visualizing complex structures as well as in enabling you to calculate a number of very important structural and electronic features of molecules. Spartan is fairly intuitive especially if you have already used Odyssey. If you would like a copy of Spartan for your personal computer, they are available from WaveFuction ( http://www.wavefun.com/ ) for $25 USD via online order. The software will be delivered to you electronically. Spartan is available on all campus computers. You may complete this part of the lab at a time convenient to you. Open Spartan, which should be in your Chemistry folder on a King’s computer. Select New from the File menu. The screen will look similar to the one shown in Figure 3.

- 8- Figure 3: The Home Screen in Spartan Student v. 8 1. Build caffeine using Spartan. You do not need to build ibuprofen. The organic model kit consists of numerous fragments which can be modified. • Begin by selecting cyclohexane from the rings button and then double-clicking anywhere in the build window. • Rings and functional groups in Spartan can easily be modified by atom replacement. For example, to change a carbon with single-bonds (an sp 3 carbon) to one with double bonds, select the sp 2 carbon fragment from the list and then double clic k on the appropriate carbon atom (not its valence) in the ring. In a similar manner, an sp 3 carbon can be replaced with an sp 3 nitrogen. • Fragments like methyl groups and double-bonded oxygen can be added by selecting them from the fragment list and clicking on the valence of the atom in the molecule where you want to add them. • To add a bond, click Make Bond in the Build menu (or use the Make Bond quick button) and then click on the valence of each of the two atoms you want to join. • When you are finished, if you have correctly constructed the molecule, Spartan will display the name caffeine at the bottom of the screen as in Figure 3. 2. Minimize the energy of the molecule by selecting Minimize from the Build menu. Instead, you might chose to use the Minimize quick button shown in Figure 3. 3. In the Setup menu, select Calculation…. Refer to Figure 4. Set the parameters to calculate the equilibrium geometry in gas using PM3. Click on the Compute IR button and then on the Submit button at the bottom. If you have not already saved the molecule, a Save-As dialog box will open. Once you chose a name for your file, Spartan will minimize the energy of the molecule and calculate the vibrational spectrum of the compound. Dialog boxes will let you know when the calculation starts and when it has finished. Once the calculation has finished, you can proceed to the next steps. The molecular fragments you can use to build a molecule include single atoms, groups, rings and more. Click on the one you want to use and then click in the working window to begin. Make Bond Minimize energy

- 9- Figure 4: Preparing to Calculate the IR Spectrum 4. Left-click and drag to rotate the molecule and/or Right-click and drag to move the molecule on the screen as required. 5. In the Display menu click on Spectra, the large green plus sign, IR, and then IR Calculated; the IR spectrum of your compound will be shown as in Figure 5. Figure 5: Displaying the IR Spectrum in Spartan The large green plus sign The program lets you know the molecule’s energy has been minimized. Successful building of caffeine will result in the name being displayed here.

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- 10- 6. Click on each important frequency (the ones from any distinguishing functional groups) to animate the molecular vibration responsible for the peak. Prepare a table in Word and list the frequency for each important peak and describe the mode of vibration. For example, the peak at 2972 cm -1 shows C-H stretching in the methyl groups attached to three of the nitrogen atoms in the molecule; the stretch is most predominant in the methyl group situated between the two C=O groups. 7. Capture the vibrational spectrum for your records and import it into your report document (likely in MS Word). If you want, you can also view the experimental spectrum for caffeine that Spartan has on file. Part B: Collecting an Infrared Spectrum Measure and record the mass of your caffeine and ibuprofen samples before you collect your IR spectra. Preparing samples for IR spectroscopy is fairly easy, but you must adhere to one rule: NO WATER! You will prepare your sample using a water-soluble salt plate (disc). Water, even from your fingerprints, will damage the disc. It is a good idea to wear gloves. Prepare and analyze your samples one at a time. There are three methods of sample preparation to collect an infrared spectrum of a solid sample. These are film cast, mineral oil mull, and KBr pellet. The least complex of these is the film cast method which you will use to analyze your samples of caffeine and ibuprofen. Prepare your sample for analysis by labeling a small (13 x 100 mm) test tube “ibuprofen”. Transfer some of your sample into the tube. Similarly prepare a tube with your caffeine sample. Dissolve each sample in 10 – 20 drops of dichloromethane and use a cork to stopper each tube. Place the tubes in a small beaker labeled with your name(s) to safely carry them into S-104. Add your names to the sign-up list on the white board in S-104 and wait for your turn using the instrument. The steps for preparing your film cast when your turn arrives are shown below. 1. Wear gloves to avoid getting fingerprints on the disc. 2. Salt plates are kept in the desiccator. Slide the lid off the desiccator and remove one KBr salt plate (disc). 3. Remove the circular compression ring from a press-on demountable sample holder. 4. In the fume hood, transfer a drop of one of your sample solutions onto the center of the KBr disc using a Pasteur pipette fitted with a rubber pipet bulb. Allow the solvent to evaporate. Repeat until you have added three drops of solution. 5. Place the KBr disc in the centre of the bottom plate of the sample holder. Replace the compression ring by gently pushing and twisting until it fits snuggly against the salt plate. 6. You will be assisted at the instrument to collect an IR spectrum but it may be useful to know that a background spectrum of an empty sample compartment will be collected prior to every sample. After collecting an IR spectrum of one component, you will need remove the sample holder from the instrument and clean the KBr disc. 1. Remove the disc from the sample holder. 2. Firmly grasp the KBr disc between two fingers. Hold the disc over a waste beaker in the fume hood and use a Pasteur pipette to drip dry chloroform all over both sides of the disc. CAUTION: This makes the disc slippery! Be careful not to drop it; they cost $60 each. 3. Blot the disc dry with a Kimwipe. Do not rub; that would scratch the plates.

- 11- Clean Up Once you are satisfied with the spectra you have generated for each of your samples, you may discard the solutions in the halogenated organic waste container . The Report: You may work with your partner to complete this report. If you decide to complete the report individually, all components must be included in each person’s submission. Your report must be uploaded to Moodle as a single file Word or pdf document. The report should include the infrared spectra you generated in lab for each component and an image of the caffeine spectrum from Spartan. In addition, complete the following tasks. • Indicate your unknown number and determine the composition of your sample mixture. What amount (weight percent) of the original mixture was ibuprofen and what percent was caffeine? Show your calculations. (2 marks) • Comment on the accuracy of the previous calculation. What experimental errors might be most responsible for any discrepancy in to the experimentally determined composition? It is not sufficient to blame “human error”; be specific. (2 marks) • Figure 6 (on page 13) shows IR spectra for pure caffeine and pure ibuprofen. Use the information in Table 1 of this handout and the structures of caffeine and ibuprofen shown in Figure 1 to determine which spectra belongs to which compound. Justify your answer by picking out three or four significant peaks which support your conclusion. These should be based on functional group assignment. Prepare a table and/or write directly on each spectrum. You do not need to, nor should you, identify every peak. (7 marks) • Figure 7 shows 13 C NMR spectra for pure caffeine and pure ibuprofen. Use the information in Figure 2 and the structures of caffeine and ibuprofen shown in Figure 1 to determine which spectra belongs to which compound. Justify your answer by picking out three or four significant peaks for distinctive functional groups which support your conclusion. Prepare a table and/or write directly on the spectra in Figure 7. You do not need to, nor should you, identify every peak. (5 marks) • Comment on what your spectra tell you about the purity of the separated components. Do you see any extra peaks in your spectra? Can you attribute any of these peaks to the other compound? Be specific. (2 marks) • For caffeine, prepare a table indicating the significant functional groups comparing the position (cm -1 ) of their peaks as evident in Figure 5, your spectra, and the spectra produced in Spartan. Are there any significant differences? (5 marks) Note: Your lab generated spectrum for caffeine may show an anomaly near 1800 cm -1 . This is a phenomenon of using the thin-film method for this compound. It is not observed on the spectra of pure caffeine which was run as a KBr disc. You will also be graded on the success of your separation: • actual recovery (4 marks) • accuracy of the determined composition (4 marks) • quality of the infrared spectra (2 marks)

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- 13- Figure 6: Infrared Spectra of Pure Caffeine (KBr pellet) and Ibuprofen (thin-film) 481.18 610.86 743.87 862.99 971.59 1023.81 1071.47 1235.16 1284.13 1357.00 1483.18 1547.44 1656.29 1701.28 2954.02 3111.52 0 10 20 30 40 50 60 70 80 90 %T 1000 1000 2000 3000 Wavenumbers (cm-1) Spectrum A 846.58 863.45 938.17 1071.52 1189.19 1231.55 1263.46 1284.16 1319.66 1366.63 1383.14 1412.79 1463.03 1513.06 1698.94 1712.24 2633.09 2869.04 2954.46 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 %T 500 1000 1000 2000 3000 Wavenumbers (cm-1) Spectrum B

- 14- Figure 7: 13 C NMR Spectra of Pure Caffeine and Ibuprofen in CDCl 3 Spectrum A Spectrum B

- 15- Chemistry 200 OBSERVATION SHEET – Separation and Analysis of a Solid Phase Mixture Name: ___________________________ Drawer #: _______________ Partner: __________________________ Initial Sample Observations and Masses Sample # __________ Sample Description: ___________________________________________________________________ Mass of Sample and Vial: _______________g Mass of Beaker __________________g Mass of Empty Vial: _______________g Mass of Sample in Beaker ____________g Mass of Sample Transferred: _______________g Observations during Extraction (What did you see? Note any colour changes, cloudiness, bubbles, explosions, loss of sample, etc.) Mass of 125 mL Erlenmeyer: _______________g Observations while adding HCl (aq) Mass of filter paper: _______________g Mass of 10 cm watch glass _______________g Final Observations (to be made at the beginning of week 2) Caffeine Appearance: __________________________________________________________ Mass of Caffeine: _______________g Ibuprofen Appearance: __________________________________________________________ Mass of Ibuprofen: _______________g

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- 17- OBSERVATION SHEET – Separation and Analysis of a Solid Phase Mixture Name: ___________________________ Drawer #: _______________ Partner: __________________________ Initial Sample Observations and Masses Sample # __________ Sample Description: ___________________________________________________________________ Mass of Sample and Vial: _______________g Mass of Beaker __________________g Mass of Empty Vial: _______________g Mass of Sample in Beaker ____________g Mass of Sample Transferred: _______________g Observations during Extraction (What did you see? Note any colour changes, cloudiness, bubbles, explosions, loss of sample, etc.) Mass of 125 mL Erlenmeyer: _______________g Observations while adding HCl (aq) Mass of filter paper: _______________g Mass of 10 cm watch glass _______________g Final Observations (to be made at the beginning of week 2) Caffeine Appearance: __________________________________________________________ Mass of Caffeine: _______________g Ibuprofen Appearance: __________________________________________________________ Mass of Ibuprofen: _______________g

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