why sodium hydrogen carbonate extract annot be used instead of sodium carbonate extract

This phenomenon will often be observed if sodium bicarbonate is used for the extraction in order to neutralize or remove acidic compounds. The reaction affords carbon dioxide (CO₂), which is a gas at ambient temperature. Pressure builds up that pushes some of the gas and the liquid out. The container should be vented immediately before the pressure build-up can cause an explosion, an ejection of the stopper on the top or excessive spillage upon opening. A similar observation will be made if a low boiling solvent is used for extraction. The shaking of the mixture increases the surface area, and therefore the apparent vapor pressure of the solvent. In addition, many extraction processes are exothermic because they involve an acid-base reaction.