According to the alternation effect observed in the melting points of the first ten aliphatic carbox — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

The melting point depends heavily on crystal lattice packing. In carboxylic acids with an even number of carbon atoms, the terminal $-CH_3$ and $-COOH$ groups lie on opposite sides of the zig-zag carbon chain. This symmetry allows for highly efficient, close packing in the crystal lattice, resulting in unusually high melting points compared to odd-carbon acids.