pre lab quiz 4 Flashcards
Caffeine is an
Alkaloi
Nitrogen containing compound which is typically an
Organic base
Caffeine forms what in acidic solution
Water soluble salt
Caffeine forms water soluble salt in
Acidic solution
It is known to be a natural stimulant and can be found in various beverages such as coffee, tea and soft drinks
Caffeine
Caffeine increase… , reduce… and increase their capacity of
Alertness
Drowsiness
Thinking
What are the other constituents found in tea leaves
Pigments
Cellulose
Chlorophylls
Tannins
In aq solution, it will form
Conjugates acid salt of caffeine
An acidic aq solution will form conjugated acid salt of caffeine which will increase
Its water solubility
In what solution do caffeine becomes neutral and has a fair solubility in water
Basic solutions
In basic solution, caffeine bcms…
Neutral
What is weakly acidic
Tannins
Tannins is weakly acidic that can be converted to
Water soluble salts
Caffeine can be extracted from the aq solution using
Dichloromethane or chloroform
Caffeine can be extracted from… using dichloromethane or chloroform
Aq solution
What are extracted tgt with caffeine may be neglected
Small amt of organic impurities
Small amt of organic impurities that are extracted tgt with caffeine may be
Neglected
The low volatility of dichloromethane and chlororform allows…
Drying easily
What allows drying easily of dichloromethane and chlororform
The low volatility
Materials needed
10teabags of same brand (not decaffeinated)
Cheesecloth/ handkerchief
Scissors
Reagents:
Anhydrous sodium carbonate (Na2CO3)
Dicholoromethane (CH2Cl2)
Iodine crystals or 15% sulfuric acid in ethanol
Methanol
Instrruments:
Electric stove
Glassware and apparatus:
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
weigh how many grams of sodium carbonate then transfer it to where
17.5g
250ml
add how much water in the sodium carbonate
125ml
use what to determine the total mass of the tea leaves in 10 tea bags
analytical balance
how long do you immerse the packed tea leaves in the boiling alkaline (Na2CO3) solution
20-30min
how do you Make sure not to burn and evaporate the solution
by setting the stove properly
after heating the mixture, cool it at
room temperature
rinse the solution with
25ml of hot distilled water
once the residue is dry, allow it to cool at room temperature then determine the mass of
crude caffeine
formula to calculate the % recovery
% recovery =(mass crude caffeine (g))/(mass of tea leaves (g)) ×100
Highly diluted aqueous solutions can be disposed
directly to the sink with the running water
what can be diluted with water then flushed down to the sink
acid wastes
what should be placed under the fume hood
Highly volatile and flammable solvents
