hydrogen iodide
Low (Technical/Scientific)Formal, Technical, Scientific
Definition
Meaning
A colorless, corrosive gas (HI) that is a binary inorganic compound of hydrogen and iodine, dissolving in water to form a strong acid.
Used industrially as a reducing agent, catalyst, and in organic synthesis; also encountered as 'hydriodic acid' when dissolved in water.
Linguistics
Semantic Notes
Primarily a chemical term; context almost exclusively scientific. 'Hydrogen iodide' refers to the pure compound (HI), while 'hydriodic acid' refers to its aqueous solution.
Dialectal Variation
British vs American Usage
Differences
No significant lexical or usage differences. Spelling is identical. Potential minor pronunciation variation in secondary stress.
Connotations
None beyond its scientific meaning.
Frequency
Equally rare in general discourse in both varieties; frequency confined to chemical contexts.
Vocabulary
Collocations
Grammar
Valency Patterns
[Substance] reacts with hydrogen iodide to form...Hydrogen iodide is used in the [process] of...The [property] of hydrogen iodide...Vocabulary
Synonyms
Strong
Neutral
Usage
Context Usage
Business
Virtually never used except in chemical manufacturing or pharmaceutical R&D reports.
Academic
Used in chemistry, chemical engineering, and materials science textbooks, lectures, and research papers.
Everyday
Extremely rare; only in very specific educational or DIY science contexts.
Technical
Core term in inorganic and organic chemistry for reactions involving halogen acids and reducing agents.
Examples
By CEFR Level
- This science book mentions hydrogen iodide.
- Hydrogen iodide is a chemical compound of hydrogen and iodine.
- In the lab, we handled hydrogen iodide gas with extreme care due to its corrosive nature.
- The regioselective cleavage of the ether bond was achieved using anhydrous hydrogen iodide as the reagent.
Learning
Memory Aids
Mnemonic
Think: H is for Hydrogen, I is for Iodine. HI is also a friendly greeting, but this compound is a strong acid, so not friendly at all!
Conceptual Metaphor
A reactive partnership (H and I) that is unstable and seeks interaction.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating word-for-word as *водородный йодид. The standard Russian term is *йодистоводородная кислота (for the acid) or *иодоводород (HI).
- The English term names the elements in the order 'hydrogen iodide', whereas the Russian adjectival form (йодистоводородный) starts with iodine.
Common Mistakes
- Mispronouncing 'iodide' as /aɪ.ə.dɪd/ (short 'i') instead of /aɪ.ə.daɪd/.
- Confusing it with 'hydrogen iodine' (incorrect).
- Using 'hydrogen iodide' to refer directly to the concentrated acid without specifying it's a solution.
Practice
Quiz
In which context is the term 'hydrogen iodide' MOST appropriately used?
FAQ
Frequently Asked Questions
Not exactly. 'Hydrogen iodide' (HI) strictly refers to the pure, gaseous compound. 'Hydriodic acid' is the name for the aqueous solution of HI in water.
It is highly corrosive, toxic, and a strong irritant to eyes, skin, and the respiratory system. It requires specialized handling in a fume hood.
Its primary uses are in organic chemistry as a reducing agent and catalyst, and in the production of iodine salts and pharmaceuticals.
It is a strong acid because the H-I bond is relatively weak and the iodide ion is large and stable, allowing the proton (H+) to dissociate completely in water.