Question

what will happen if i use NaOH in the place of Na2CO3 in caffeine extraction from tea?

Answer 1

The sodium carbonate acts as a base - you could use sodium hydroxide instead. When you boil tea leaves tannins dissolve in the water as well as the caffeine. If you do not use a base the tannins will also be extracted from the solvent (i.e. methylene chloride) used in the subsequent extraction.