Nomenclature
CAS number: 10034-85-2
HI; mol wt 127.91.
H 0.79%, I 99.21%.
Description and references
A soln of hydrogen iodide in water. Marketed
in various concns, e.g., 57% HI, d 1.7; 47%, d 1.5; 10%,
d 1.1. Prepd by absorption of hydrogen iodide gas in water or by
the action of iodine on hydrogen sulfide according to the eq H2S + I2 → 2HI + S: Heisig, Frykholm, Inorg. Synth. 1, 157 (1939). See also Hydrogen Iodide.
Properties
Colorless when freshly made, but rapidly turns
yellowish or brown on exposure to light and air. This discoloration
can be prevented by the addition of about 1.5% hypophosphorous acid
(H3PO2). Concd solns that have been stored
for some time are usually opaque from oxidation, they may be regenerated
with hypophosphorous acid: Foster, Nahas, Jr., Inorg. Synth. 2, 210 (1946). Corrosive. Keep protected from light and air, preferably
not above 30°. Miscible with water or alcohol. Dissolves
iodine. The azeotrope (constant-boiling acid) bp760 127°, d 1.70, contains 56.9% HI. Strong, corrosive
acid, attacks natural rubber. 0.1 molar soln, pH 1.0.Caution
Strong irritant.Use
Reducing agent, manuf of inorganic iodides, pharmaceuticals,
disinfectants. The 57% acid is also used for analytical purposes,
such as methoxyl determinations.
Therapeutic Category
Expectorant.
Keywords
Expectorant