extraction of caffeine from tea bag

[rickysingh007]

we extracted caffeine from tea bag and need to answer following questions for lab. 

2.  why was sodium carbonate added to the solution that contained H2O and tea bag.

3.  the crude caffeine isolated from tea often has green tinge. why?

4.  why was melting point of isolated  lower than the literature value (236 celcius)

5.  what would happen to the caffeine if the sublimation step were performed at atmospheric pressure?

[chrisf]

2) The sodium carbonate helps to precipitate out the acidic tannins that come along with tea/caffeine.

3) The undecomposed chlorophyll is soluble in the dichloromethane that you probably used.