What is the Difference Between Benzoic Acid and Sodium Benzoate?

Benzoic acid and sodium benzoate are both organic compounds with the aromatic benzene ring and a carbonyl group. They differ in their solubility in water at room temperature and their irritant properties. Key differences between benzoic acid and sodium benzoate include:

1. Irritation: Benzoic acid is slightly irritating to the skin and is irritating to the eye, while sodium benzoate is not irritating to the skin and is only a slight eye irritant.
2. Solubility in water: Benzoic acid is poorly soluble in water at room temperature, whereas sodium benzoate is soluble in water.
3. Molar mass and appearance: Sodium benzoate has a molar mass of 144 g/mol and appears as a white crystalline powder, odorless, with a melting point of 410 °C.
4. Interactions with interfaces: Both benzoic acid and benzoate can penetrate membrane/water interfaces, but benzoic acid can penetrate much deeper, making it more readily able to traverse a membrane.

Both benzoic acid and sodium benzoate have antimicrobial properties and are used as preservatives in various food and beverage products, such as fruit juice, carbonated drinks, and pickles.

Comparative Table: Benzoic Acid vs Sodium Benzoate

Here is a table comparing the differences between benzoic acid and sodium benzoate:

Both benzoic acid and sodium benzoate are organic compounds with an aromatic benzene ring substituted with a carbonyl group. Benzoic acid is the simplest aromatic carboxylic acid, while sodium benzoate is the sodium salt of benzoic acid. The key difference between the two is their solubility in water: benzoic acid is poorly soluble at room temperature, while sodium benzoate is soluble in cold water. This difference in solubility makes sodium benzoate a more suitable food preservative, especially in slightly acidic conditions.