Substance profile
Hydrogen iodide
Hydrogen iodide is a colorless gas; fumes in moist air with an acrid odor.
01 · Identification
What Hydrogen iodide is
Hydrogen iodide is a colorless gas; fumes in moist air with an acrid odor. Its molecular formula is HI and its molecular weight is 127.912 g/mol. It boils at -35.1 °C, melts at -50.8 °C.
Under the GHS it carries the signal word Danger. It is classed as corrosives.
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H314 | Causes severe skin burns and eye damage. |
03 · Physical and chemical properties
Hydrogen iodide properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | -35.1 °C (-31.2 °F) | at 760 mmHg | HSDB |
| -35.5 °C (-31.9 °F) | ICSC | ||
| -35.38 °C (-31.7 °F) | at 760 mmHg | DOE PAC | |
| Melting point | -50.8 °C (-59.4 °F) | HSDB | |
| Density | 5.66 g/cm³ | at 25 °C | DOE PAC |
| 0.0057 g/cm³ | at 0 °C | HSDB | |
| 1.7 g/cm³ | at 127 °C | HSDB | |
| Solubility | Solubility in water, g/100ml at 20 °C: 42 (freely soluble) | at 20 °C | ICSC |
| Extremely soluble in water; 234 g/100 g water at 10 °C; 900 g/100 g water at 0 °C | at 10 °C | HSDB | |
| Vapor pressure | 5498 mmHg | at 20 °C | ICSC |
| 5938 mmHg | at 25 °C | HSDB | |
| 5940 mmHg | at 25 °C | DOE PAC | |
| Vapor density | 4.4 (air = 1) | HSDB | |
| Critical temperature and pressure | 151 °C (303.8 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Handling and storage
Storing and handling Hydrogen iodide
Storage conditions
Hydroidic acid must be stored to avoid contact with strong acids (such as hydrochloric, sulfuric and nitric), chemically active metals (such as potassium, sodium, magnesium and zinc), and strong oxidizers (such as chlorine, bromine, and fluorine) since violent reactions occur. Store in tightly closed containers in a cool, well vented area away from heat and moisture. Protect storage containers from physical damage. Procedures for the handling, use and storage of cylinders should be in compliance with OSHA 1910.101 and 1910.169 as with the recommendations of the Compressed Gas Association.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
REACTS WITH WATER OR STEAM TO PRODUCE TOXIC & CORROSIVE FUMES.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Hydrogen iodide in the storage compatibility matrix →