The reaction between hydrogen gas (H₂) and iodine gas (I₂) to produce hydroiodic acid (HI) can be represented by the chemical equation:
\[ \text{H}_2(g) + \text{I}_2(g) \rightarrow 2 \text{HI}(g) \]
In this reaction, one molecule of hydrogen reacts with one molecule of iodine to produce two molecules of hydroiodic acid.
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