Experiment no. 4: Extraction of Caffeine from Tea Leaves

Question 1

“______ out” of a substance from one phase by another phase

Fill in the blank and identify which word is described.

Answer 1

Pulling, extraction

Question 2

removal of a desired compound from a solid/liquid mixture using what?

Answer 2

solvent

Question 3

extraction of an organic compound from one liquid phase using another liquid

Answer 3

Liquid-liquid extraction

Question 4

Device commonly used from liquid-liquid extraction?

Answer 4

Separatory funnel

Question 5

Give the four (4) uses of separatory funnel

Answer 5

1. aqueous solution & extracting solvent are mixed inside
2. mixture is shaken w/ frequent venting
3. Two layers separated, lower layer is drained into vessel.
4. Exhaustive extraction allows more efficient extraction.

Question 6

What is the extracting solvent in the aqueous solution?

Answer 6

Dichloromethane (DCM)

Question 7

What is the aqueous solution?

Answer 7

Tea powder

Question 8

Why is dichloromethane (DCM) used to extract caffeine?

Answer 8

DCM is used because it is more soluble than water (DCM= 140mg/mL; water= 22mg/mL)

Question 9

organic bases; form water-soluble salts when treated with acids

Answer 9

amines

Question 10

Physiologically active nitrogen containing compounds that can be extracted from plants using aqueous acid

Answer 10

Alkaloids

Question 11

naturally occurring stimulants

Answer 11

xanthines

Question 12

an alkaloid; belongs in xanthines group; is extracted in the experiment

Answer 12

caffeine

Question 13

title of the experiment

Answer 13

Extraction of Caffeine from Tea Leaves

Question 14

Purpose of caffeine

Answer 14

1. stimulants
2. vasolidator
3. diuretic

Question 15

stimulants can also be found in? (5)

Answer 15

1. coffee
2. tea
3. cocoa
4. chocolate drink
5. soft drinks

Question 16

Major components of tea leaves (4)

Answer 16

1. caffeine
2. chlorophyll & pigments
3. cellulose
4. tannins

Question 17

From the components of tea leaves, which are water-soluble? Which are not?

Answer 17

caffeine & tannins

Question 18

high molecular weight phenolic compounds

Answer 18

tannins

Question 19

Melting point of caffeine

Answer 19

227-228 degrees Celsius

Question 20

Solubility of caffeine to water

Answer 20

22 mg/mL

Question 21

Solubility of caffeine to boiling water

Answer 21

670 mg/mL

Question 22

Solubility of caffeine to DCM

Answer 22

140 mg/mL

Question 23

weakly basic

Answer 23

caffeine

Question 24

weakly acidic

Answer 24

tannins

Question 25

extraction method by boiling plant material to dissolve the chemicals of the material

Answer 25

decoction

Question 26

what is extracted from tea leaves

Answer 26

caffeine

Question 27

not soluble in water, but highly soluble in caffeine

Answer 27

DCM

Question 28

tannins are converted into water-soluble salts using?

Answer 28

sodium carbonate

Question 29

when tannins are converted into water-soluble salts, they become _______

Answer 29

anionic surfactants

Question 30

surfactants are formed because of this compound, and why

Answer 30

Dichloromethane, water-insoluble

Question 31

surfactants cause

Answer 31

emulsions

Question 32

how can emulsions be avoided

Answer 32

Mixing or shaking gently

Question 33

How to remove emulsions? (2)

Answer 33

1. Allow the mixture to

Question 34

How to remove emulsions? (2)

Answer 34

1. Allow the mixture to stand for some time
2. Make the aqueous solution highly ionic by adding sodium chloride

Question 35

What is added to the aqueous layer to make it highly ionic and remove emulsions

Answer 35

Sodium chloride (NaCl)

Question 36

Breaks small scale amulsion; separating molecules having different densities by spinning them in solution around an axis

Answer 36

Centrifugation