What is the objective of including sodium carbonate to the water-teaextract?Draw the basic reaction equation that outcomes from theaddition that the sodium carbonate.

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List one benefit and one disadvantage of shower theseparatory funnel during extraction

List 2 different varieties of analyses that might be lugged outto confirm the recrystallized solid is indeed caffeine

List two various methods as well as the one supplied in thisexperiment to isolation caffeine native tea.


Answer-

Sodium carbonate is included to theextraction medium to ensure that the acidiccomponents in the tea pipeline remainwater soluble and also that caffeine is the freebase.

Sodium carbonate is basic. Tannins space acidiccompounds with a high molecular weight that have an –OH directlybound come an aromatic ring. Because that this add around 10g, ofsodium carbonate to your aqueous teaextract. You should notice a distinct fizzing once you addthe an initial of the sodium carbonate, together itreacts through the acidic tannins to relax carbondioxide gas. Simmer the solution for 5 minutes and then boil mostof the water off.

(A) advantage of utilizing shaking the separatory funnel,

1)Ability to different at least two immiscible liquids indigenous eachothers.

2) It can be activate easily and also rapidly.

3) it is transparent to observe different layers easily.

4) The top layer or the lower layer can be selectivelyremoved. The top layer is removed by the stopper and the lower bythe stopcock.

(B) The significant disadvantage of utilizing shaking the separatoryfunnel is the separation the phases might be no extremelyaccurate.

1-Recrystalization Method-Add 5-8 mL the hotacetone come dissolve the rudely caffeine andtransfer the solution to a 50 mL Erlenmeyer flask forrecrystallization. Add a couple of drops that petroleumether until you with the cloud allude (caffeine isless dissolve in this combined solvent and is just beginning toprecipitate) and also then cool the solution.

2-Recrystalization Method-Place thetea pipeline in a 125-ml Erlenmeyer flask. Include 20 mldichloromethane and 10 ml 0.2 M NaOH. Extraction: Seal the flaskand gently swirl it because that 5-10 minute to allow the solvent mixtureto penetrate the leaves. Caffeine disappear in thesolvent, while many of the various other compounds in the pipeline donot.

Procedure :- Isolation of Caffeine native Tea

Reagents Required:

Dichloromethane.Anhydrous salt sulfite.Distilled water.

Materials Required:

Tea bags.Beaker (500ml).Hot plate.Separating funnel.Melting allude apparatus.Cool the aqueous systems to near room temperature.Continue cooling in an ice box, the tea should be cool (20° C)before coming in call with dichloromethane (boiling allude = 40°C).Extract the solution three times with 30-mL sections ofdichloromethane (CH2Cl2). Execute not acquire dichloromethane top top yourhands.

Tea bags are supplied as the source of caffeine for thisexperiment.

Extraction step:

a. The tea systems is poured into a separating funnel and also 20mlof dichloromethane is included to it. The mixture will different intotwo great - the height layer is the tea layer and also bottom layer is thedichloromethane because it is denser 보다 tea.b. Eliminate the funnel native the stand and keep your fingers top top thestopper and carefully shiver the separating funnel.c. Vent the separating funnel regular (every 30 sec) torelieve vapour pressure developed inside the funnel.d. When the components have to be sufficiently shaken location theseparating funnel earlier on the ring stand and also let the two layersseparate.e. Drain the bottom layer into a conical flask because now thecaffeine is extracted into the dichloromethane layer. Cover themouth the the conical flask to avoid evaporation of solution.f. Repeat procedures a) v e) twice.

9.Dry the merged dichloromethane options with anhydrousSodium sulfite. Add around 1 teaspoon of the drying agent till itno much longer clumps together at the bottom the the flask. Mix fine andleave it for 10 minutes.

10.Decant the dichloromethane into a conical flask (100ml).Evaporate the dichloromethane solvent in a hot water bath.

11.When every the solvent is eliminated you observe a residue ofyellowish environment-friendly - white crystalline caffeine.

Sublimation step:

a.Take the conical flask containing crystalline caffeine.b.Sublime the crude oil caffeine at atmospheric push by placing theflask straight on a pre-heated warm plate. Caffeine melts in ~ 238°Cand sublimes at 178°C.c.Collect your sublimed caffeine by keeping a test tube on themouth the the conical flask.d.White vapour that caffeine difficult onto the test tube and thewalls the the conical flask is observed.e.Now cool the conical flask.

12.Take a clean watch glass and also record its weight in a weighbalance.

13.Now strip off the caffeine native the conical flask and thewalls the the test tube into the watch glass utilizing a spatula.

14.Record the weight of the watch glass + caffeine in a weighbalance and also then discover out the load of extracted purecaffeine.

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15.The melting point of the extracted caffeine is determinedusing the melting point apparatus.