C7H5O2Ca

C7H5O2Ca is the empirical formula for calcium benzoate, commonly written as Ca(C7H5O2)2. The empirical formula reflects the ratio of atoms in the compound, while the conventional molecular formula shows the full salt: two benzoate (C7H5O2−) ligands balanced by one Ca2+ ion. Calcium benzoate is a white, crystalline solid used widely as a salt of benzoic acid.

Production and structure

Calcium benzoate is prepared by neutralizing benzoic acid with a calcium salt such as calcium hydroxide or calcium carbonate. The resulting compound is the calcium salt of benzoic acid with the formula Ca(C7H5O2)2. In solution, the benzoate groups can act as buffers and may release benzoic acid under acidic conditions.

Applications

Calcium benzoate functions as a preservative in foods and beverages (often cited as E213 in regulatory contexts) due to the antimicrobial activity of the benzoate ion. It is also used in some cosmetic and pharmaceutical formulations as a stabilizer or preservative, and can serve as a source of benzoate in certain applications.

Properties and behavior

Calcium benzoate is sparingly soluble in water and is relatively stable under ordinary storage conditions. In acidic environments, it can convert to benzoic acid and calcium ions. The compound is generally regarded as to have low acute toxicity, with safety regulated by food and cosmetic authorities within approved limits.

Safety and regulation

As a food additive and preservative, calcium benzoate is subject to regulatory limits that vary by jurisdiction. Like other benzoates, it should be used in amounts consistent with safety guidelines to minimize potential adverse effects in sensitive individuals.

See also

Benzoic acid, Sodium benzoate, Calcium benzoate (E213)