Question

1. Explain why base is needed in an acid base extraction to separate the components of a mixture? Why is acid often added at the end to obtain the final product?

2. Why does foaming occur when acid is added to a bicarbonate extraction? Explain with chemical equations

Answer 1

(1) In an acid-base extraction method, we can separate both acid and base from a mixture. To do this, we have to take the help of acid and base. To extract acid from the mixture, we need the help of base to separate it and followed by acid treatment and vice-versa.

Let we have a mixture of benzoic acid and other neutral compounds.

first, we dissolve the acid +neutral compound in ether(organic solvent). then the base is added to it. the acid will react with the base forming a salt . the get undissolved in an organic solvent(inorganic ). salt get dissolved in water and it comes to aqous layer . the aqous layer is separated from the organic layer and treated with acid to get back the acid and the acid get dissolved in organic solvent once again..solvent is evaporated to get the acid.

a base is needed to make salt. acid is needed to get back acid from the salt.

(2) foaming is occurred due to the formation of carbon dioxide(CO2).

NaHCO3 +CH3COOH (l) = CH3COONa (aq) +H2O (l) +CO2 (g)

due to the formation of a gas in the medium, it get foammed.