increasing down the group. Hydrofluoric acid is complicated because its strength depends on the concentration owing to the effects of homoconjugation. As solutions in non-aqueous solvents, such as acetonitrile, the hydrogen halides are only modestly acidic however. Similarly, the hydrogen halides react with ammonia (and other bases), forming ammonium halides: HX + NH3 → NH4X In organic chemistry, the hydrohalogenation reaction is used to prepare halocarbons. For example, chloroethane is produced by hydrochlorination of ethylene: C2H4 + HCl → CH3CH2Cl See also Pseudohalogen Hypohalous acid group 13 hydrides group 14 hydrides group 15 hydrides group 16 hydrides References Nonmetal halides Hydrogen compounds Diatomic molecules