pre lab quiz 4

Question 1

Caffeine is an

Answer 1

Alkaloi
Nitrogen containing compound which is typically an
Organic base

Question 2

Caffeine forms what in acidic solution

Answer 2

Water soluble salt

Question 3

Caffeine forms water soluble salt in

Answer 3

Acidic solution

Question 4

It is known to be a natural stimulant and can be found in various beverages such as coffee, tea and soft drinks

Answer 4

Caffeine

Question 5

Caffeine increase… , reduce… and increase their capacity of

Answer 5

Alertness
Drowsiness
Thinking

Question 6

What are the other constituents found in tea leaves

Answer 6

Pigments
Cellulose
Chlorophylls
Tannins

Question 7

In aq solution, it will form

Answer 7

Conjugates acid salt of caffeine

Question 8

An acidic aq solution will form conjugated acid salt of caffeine which will increase

Answer 8

Its water solubility

Question 9

In what solution do caffeine becomes neutral and has a fair solubility in water

Answer 9

Basic solutions

Question 10

In basic solution, caffeine bcms…

Answer 10

Neutral

Question 11

What is weakly acidic

Answer 11

Tannins

Question 12

Tannins is weakly acidic that can be converted to

Answer 12

Water soluble salts

Question 13

Caffeine can be extracted from the aq solution using

Answer 13

Dichloromethane or chloroform

Question 14

Caffeine can be extracted from… using dichloromethane or chloroform

Answer 14

Aq solution

Question 15

What are extracted tgt with caffeine may be neglected

Answer 15

Small amt of organic impurities

Question 16

Small amt of organic impurities that are extracted tgt with caffeine may be

Answer 16

Neglected

Question 17

The low volatility of dichloromethane and chlororform allows…

Answer 17

Drying easily

Question 18

What allows drying easily of dichloromethane and chlororform

Answer 18

The low volatility

Question 19

Materials needed

Answer 19

10teabags of same brand (not decaffeinated)
Cheesecloth/ handkerchief
Scissors

Question 20

Reagents:

Answer 20

Anhydrous sodium carbonate (Na2CO3)
Dicholoromethane (CH2Cl2)
Iodine crystals or 15% sulfuric acid in ethanol
Methanol

Question 21

Instrruments:

Answer 21

Electric stove

Question 22

Glassware and apparatus:

Answer 22

2 beaker 600ml
2 beaker 250ml
2 stirring rod
Graduated cylinder 100ml
Beaker 100ml
Sepratory funnel 250ml
Graduated cylinder 10ml
Water trough
Stainless water bath
Thermometer

Question 23

weigh how many grams of sodium carbonate then transfer it to where

Answer 23

17.5g
250ml

Question 24

add how much water in the sodium carbonate

Answer 24

125ml

Question 25

use what to determine the total mass of the tea leaves in 10 tea bags

Answer 25

analytical balance

Question 26

how long do you immerse the packed tea leaves in the boiling alkaline (Na2CO3) solution

Answer 26

20-30min

Question 27

how do you Make sure not to burn and evaporate the solution

Answer 27

by setting the stove properly

Question 28

after heating the mixture, cool it at

Answer 28

room temperature

Question 29

rinse the solution with

Answer 29

25ml of hot distilled water

Question 30

once the residue is dry, allow it to cool at room temperature then determine the mass of

Answer 30

crude caffeine

Question 31

formula to calculate the % recovery

Answer 31

% recovery =(mass crude caffeine (g))/(mass of tea leaves (g)) ×100

Question 32

Highly diluted aqueous solutions can be disposed

Answer 32

directly to the sink with the running water

Question 33

what can be diluted with water then flushed down to the sink

Answer 33

acid wastes

Question 34

what should be placed under the fume hood

Answer 34

Highly volatile and flammable solvents