Tetrachloroiodic acid

Tetrachloroiodic acid is an inorganic compound, a polyhalide acid with the formula HICl₄. In addition to an anhydrous form, an orange crystalline tetrahydrate is known. It is unstable in air.^[1]

Tetrachloroiodic acid

Identifiers
3D model (JSmol)	Interactive image
InChI InChI=1S/Cl4I/c1-5(2,3)4/q-1/p+1 Key: VEFRWHPHQIYAIZ-UHFFFAOYSA-O
SMILES [H+].[Cl-][I3+]([Cl-])([Cl-])[Cl-]
Properties
Chemical formula	HICl4
Appearance	Orange crystals (hydrate)
Melting point	19 °C (66 °F; 292 K) (hydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

Tetrachloroiodic acid may be formed by dissolution of iodine trichloride in concentrated hydrochloric acid:^[2]

ICl₃ + HCl → HICl₄

Tetrachloroiodic acid may also be made by passing chlorine through a solution of iodine in concentrated hydrochloric acid :

I₂ + 3 Cl₂ + 2 HCl + 4 H₂O → 2 HICl₄

Physical properties

Tetrachloroiodic acid forms a crystal hydrate which has orange crystals that are unstable in air and melt by dissolving in their own water of crystallization at 19 °C.^[2]

See also

• Iodine trichloride