Title: Hydriodic Acid
CAS Registry Number: 10034-85-2
Molecular Formula: HI
Molecular Weight: 127.91
Percent Composition: H 0.79%, I 99.21%
Literature 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). 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.
Boiling point: bp760 127°
Density: d 1.70
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.
Therap-Cat: Expectorant.
Keywords: Expectorant. |