Hydrogen fluoride (HF) reacts with water (H₂O) to form hydronium ions (H₃O⁺) and fluoride ions (F⁻). This is an acid-base reaction, where HF acts as a weak acid and water acts as a base.

Here's the chemical equation:

HF (aq) + H₂O (l) ⇌ H₃O⁺ (aq) + F⁻ (aq)

Explanation:

* HF donates a proton (H⁺) to water, forming H₃O⁺ (hydronium ion).

* H₂O accepts the proton from HF, forming F⁻ (fluoride ion).

The reaction is an equilibrium reaction, meaning it can proceed in both directions. However, HF is a weak acid, so the equilibrium lies to the left, meaning there are more HF and H₂O molecules than H₃O⁺ and F⁻ ions in solution.

Important Note:

* HF is a very corrosive acid and should be handled with extreme caution. Its reaction with water releases heat, making the solution even more corrosive.

* Due to the strength of the H-F bond, HF doesn't completely ionize in water like strong acids like HCl or HNO₃. This is why it's considered a weak acid.