When naming an acid, what does the prefix hydro tell you?

2 Answers
Apr 6, 2017

Concerning or using water (Longman Dictionary of English Language and Culture, 1992).


Hydrochloric acid (HCl) or Hydrofluosilicic acid (H2SiF6) are acids that contain hydrogen.


Longman Dictionary (1992) Longman Dictionary of English Language and Culture. Essex, England.

Apr 6, 2017

It denotes that it is an acid formed via the dissolution of a hydrogen halide in water.


The hydrogen halides are diatomic compounds of hydrogen and either chlorine, fluorine, bromine or iodine (or astatine to be completely accurate).

Hydrogen halides dissolve in water and easily dissociate yielding #H_3O^+# ions (and halide ions in solution). Therefore the solutions are known as "hydrohalic acids" (hydrochloric, hydrofluoric, hydrobromic, etc).

NB: "Hydro" does not simply denote the presence of a hydrogen atom in the molecule. Acetic (ethanoic) acid has hydrogen atoms in the molecule, but is not named using the prefix "hydro".