Question

Why do you think a base (sodium carbonate) is added to the caffeine energy drink mixture before the extraction with dichloromethane in the separatory funnel?

A If caffeine is protonated, it will be charged and thus more polar and also more soluble in the aqueous phase instead of the organic phase

B If caffeine is a sodium salt, it will be charged and thus more polar and also more soluble in the aqueous phase instead of the organic phase

C If caffeine is a carbonate salt, it will be charged and thus more polar and also more soluble in the aqueous phase instead of the organic phase

D Both C and D are correct

In the lab manual, it states that caffeine is harmful is swallowed, yet many of us drink coffee regularly. Is the lab manual and the Safety Data Sheet wrong, or should coffee be made a controlled substance by the FDA and all Starbucks closed asap?

A Yes, its a true miracle we are still alive by lunchtime after having AM coffee

B In the lab, we are dealing with much more concentrated and/or purer caffeine than one normally ingests.

C Caffeine is indeed poisonous above certain threshold levels. The amounts handled in the lab are higher than levels in coffee.

D Both B and C are correct

Why is it important to be careful about contact with methylene chloride?

A It may cause cancer

B It is readily absorbed though the skin

C It is highly volatile

D all of the above

Answer 1

1. A base is added is caffeine extraction before the extraction with dichloromethane because of the presence of tannins which are acidic in natrure which passes into the aqueous phase. Thus if base is not added tannins will be extracted alongwith caffeine. This is the reason why base is added.

The above reasons do not match with the said reason. Hence none of the options are correct.

2. In lab we deal much purer and crude form of caffeine which is not suitable for consumption and moreover intake greater than threshold level is poisonous for consumption. Hence both B and C options are correct.

3. Exposure to Methylene chloride is harmful because it may cause cancer and skin irritation. Moreover it is highly volatile

Hence option D is the correct answer.