Water spontaneously ionizes into hydroxide anions and hydrogen cations. Sodium acetate dissociates into sodium ions and acetate ions in water. Sodium ions rarely react with hydroxide ions, while acetate ions combine with hydrogen ions to form acetic acid.
The key difference between acetate and acetic acid is that acetic acid is a neutral compound whereas acetate is an anion with a net negative charge. Acetic acid is an organic compound that helps to make vinegar, and the acetate ion is the conjugate base of acetic acid.
Sodium acetate is an alkaline salt; the acetate ion deprotonates water, increasing the pH of the solution. Basic salts are formed in the neutralization reaction between a strong base and a weak acid.
The structural and thermodynamic aspects of the hydration of acetic acid (CH3COOH) and acetate ion (CH3COO−) were investigated using the 1D-RISM integral equation method. It was found that the average number of water molecules in the hydrophobic hydration shell of single-bonded CH3 groups was 8.9 for acetic acid and 10 for acetate. The average number of hydrogen bonds formed by single-bonded COOH groups was 2.5 compared to 6 for single-bonded COO-, indicating that deprotonation of acetic acid resulted in increased hydrogen bonding of water molecules to the carboxylate moiety. This step involves a significant reorientation of the water molecules around the carboxyl groups. The free energies of hydration and water ionization constants calculated with the semi-empirical correction set are in reasonable agreement with the available experimental results.
