Why concentrated sulphuric acid is used as a catalyst instead of dilute sulphuric acid or a weak acid in esterification?

The reversible reaction of carboxylic acid + alcohol + right-left harpoons + ester + water is known as esterification.

Le Chatelier's principle is applicable in this case: a higher concentration of water will cause the position of equilibrium to shift to the left, resulting in less ester being formed; a higher concentration of acid will cause the position of equilibrium to shift to the right, resulting in more ester being formed.

Concentrated sulfuric acid is used as a catalyst in esterification reactions because it is a strong dehydrating agent. It removes water from the reaction mixture, shifting the equilibrium towards the formation of the ester. Dilute sulfuric acid or weak acids are not effective catalysts for esterification because they do not have the same dehydrating properties as concentrated sulfuric acid.

Concentrated sulfuric acid is used as a catalyst in esterification reactions due to its strong acidic properties and dehydrating ability. It helps drive the esterification reaction forward by removing water from the reaction mixture, which is crucial for achieving higher yields of ester product. Dilute sulfuric acid or weak acids lack the same dehydrating power and may not be as effective in promoting the esterification reaction. Additionally, concentrated sulfuric acid is less likely to interfere with the desired reaction pathway compared to weaker acids, which could potentially lead to side reactions or incomplete conversion of reactants to products.