Fischer esterification, why would it result in a poor yield of ester?

Question

Sodium carbonate was added to extract the acid.

Answer 1

I suspect you used acid catalysis ( H2SO4 ) to drive the formation of the ester. This is a two-edged sword in that the acid catalyst in comjunction with the water formed by the condensation of the fatty acid and alcohol can drive the reaction the other way. A good way to drive the reaction to completion is to distill the water off as it is formed ..or if the ester is low boiling distil it off as it is formed .This prevents any reversibility.