So what are epsom salts, anyway?

Arnold’s question about the hole in his leg reminded me of a question I’ve been meaning to ask: what are epsom salts, anyway? what makes them different from regular salt? and how are epsom salts used for medical treatments? (not asking about any partiuclar medial case or anything - just curious.)

Magnesium sulphate

A “salt” is a chemical consisting of a molecule with metal (or a group acting like a metal) replacing the hydrogen in an acid. For example, HCl (one atom of H and one of Cl) is the chemical formula for hydrocloric acit. When the hyrogen, H, is replaced by sodium, Na, the result is NaCl, common table salt.

Sulphuric acid’s chemical formula is H[sub]2[/sub]SO[sub]4[/sub]. When the H’s are replaced by magnesium, Mg, the result is magnesium sulphate, MgSO[sub]4[/sub]. When this moleculte is hydrated, that is water molecules are attached to the magnesium sulphate molecule, the result is Epsom Salt, MgSO[sub]4[/sub]∙7H[sub]2[/sub]O. The water of hydration can be removed, such as by heating, without affecting the basic subtance of the magnesium sulphate.

There. I have just exhausted what’s left of two years of college chemistry. If you have further questions you will have to wait for a chemist to come along. :slight_smile: