Question

#1-6

1. Outline a separation scheme for isolating caffeine from tea. Use a flowchart similar in format to that shown in Technique 2, Section 2.2. 2. Why was the sodium carbonate added in Experiment 13A? 3. The crude caffeine isolated from tea often has a green tinge. Why? 4. What are some possible explanations for why the melting point of your isolated caffeine was lower than the literature value (236°C)? 5. An alternative procedure for removing the tannins and gallic acid is to heat the tea leaves in nins and gallic acid to form insoluble calcium salts of these acids. If this procedure were used, what additional step (not done in this experiment) would be needed in order to obtain an aqueous tea solution? 6. What would happen to the caffeine if the sublimation step were performed at atmospheric pressure?

Answer 1

the The sodium carbonate act as a base. so, if we use sodium hydroxide ist instead of Na coz then boil tea leaves tannins dissolved in the water as well as the caffeine. It donot use a base e tannins will also be extracted in to the Solvent used in the subsequent extraction, the base converts the tanning into their Sodium salts - being ionic those eets not soluble in solvents so remain in aqueus Layer during extrechim. and purer Caffone to be extrached. The coude caffine tea often has a Chlorophyll that tea leaves. isolated from the green tog tinge due to naturally present in