Question

Introduction: Pre-lab Questions Turn in typed responses in the beginning of lab. Answer in complete sentences. Show your work in pen where applicable. 1. What other compounds are extracted along with caffeine into the tea? Use what you know about the relative polarity of the functional groups within these compounds to determine the final destination of the following compounds: cellulose, tannins, chlorophylls, sodium carbonate. Do the majority of these compounds end up in the tea bag, filtered solid, aqueous layer, or organic layer? 2. What is the role of sodium carbonate in the extraction? Draw the balanced reaction of sodium carbonate with a phenol (PhOH). 3. Why is sodium chloride added before extraction the aqueous layer with DCM? How does magnesium sulfate break emulsions? 4. One gram of caffeine dissolves in 55 mL of water, 7 mL of DCM, 530 mL of diethyl ether, and 100 mL of benzene. Convert the solubility of caffeine in these four solvents into units of mg/mL. Estimate the partition coefficient of caffeine between DCM and water, diethyl ether and water, and benzene and water. Which is the optimal solvent to extract caffeine from an aqueous solution? Why? 5. What is sublimation? Why is it possible to sublime caffeine? List another compound that sublimes near ambient pressure. In-lab Questions Copy the questions into your notebook before lab. Complete in the lab notebook before leaving lab then type responses for the report. Answer in complete sentences and show your work in pen. Re-read the introduction to the experiment and copy the appropriate equations along with the questions. 1. Report the mass of the crude extract and the total mass of dry tea leaves used in the extraction. Calculate the percent recovery of the crude extraction of caffeine from dry tea leaves (eq. 4). 2. Report the theoretical amount of caffeine in one bag of Lipton tea. Calculate the theoretical recovery of extraction (eq. 4) using the amount of caffeine on the ingredients label (or look online) and the mass of dry leaves in one tea bag. Is the percent recovery comparable to the theoretical recovery? 3. Describe the appearance of the crude extract and the purified product. Calculate the percent recovery of the sublimation process (eq. 5). 4. Report the theoretical amount of caffeine that could be extracted from six Lipton tea bags (amount in one tea bag is listed on the box and online). Calculate the percent recovery based on the amount of pure caffeine obtained vs. the theoretical amount (eq. 6). Briefly comment on the success of the experiment. 

1 bag tea mass : 2.13 g

we used 6 bag (lipton tea)

0.12 g  organic extract

Mass of pure caffeine: 0.0159g

Mass of crude extrac :0.12 g

Answer 1

So we have coffee which contains caffeine and tannine so by layer separation technique we can separate both compound with purity this process is known as secondary separation.

Step1. We have mixture of caffeine and tannine in coffee but caffeine don't have any functional group that can affect by acid or base that means we can say that caffeine is neutral compound. So by addition of aqueous Na2CO3 solution it will peak the proton of tanning and will form sodium salt. As we know that salt are soluble in water so tannine salt will go water and caffeine which is unreacted which will go to ethyl acetate layer so just evaporate the ethyl acetate layer to get caffeine from mixture of caffeine and tannine.

Step 2. Now we have aqueous layer which contains sodium salt of tannine by addition of aqueous HCl Tannine will get protonated and it's become organic compound which will soluble in ethyl acetate, so separate ethyl acetate layer and concentrate to get tannine.

So in this way we can separate caffeine from coffee.