The neutralization reaction between hydroiodic acid (HI) and sodium hydroxide (NaOH) can be represented by the following balanced equation:
\[ \text{HI (aq)} + \text{NaOH (aq)} \rightarrow \text{NaI (aq)} + \text{H}_2\text{O (l)} \]
In this reaction, HI, an acid, reacts with NaOH, a base, to produce sodium iodide (NaI) and water (H₂O). Notice that all the reactants and products are either in aqueous (aq) or liquid (l) states, as specified.