To determine the acid-conjugate base pair in the reaction
[tex]\[ HF + H_2O \rightarrow H_3O^+ + F^- \][/tex]
we need to identify which compounds differ by one hydrogen ion (H⁺).
### Step-by-Step Analysis:
1. Identify the participants:
- Acid: A substance that donates a hydrogen ion (H⁺).
- Base: A substance that accepts a hydrogen ion (H⁺).
2. Examine the reaction:
- HF (hydrofluoric acid) donates a hydrogen ion (H⁺) to water (H₂O).
- The resulting products are [tex]\( H_3O^+ \)[/tex] (hydronium ion) and [tex]\( F^- \)[/tex] (fluoride ion).
3. Identify the pairs:
- HF donates a hydrogen ion and becomes [tex]\( F^- \)[/tex].
- Therefore, the pair [tex]\( HF \)[/tex] (acid) and [tex]\( F^- \)[/tex] (conjugate base) differ by one hydrogen ion [tex]\( H⁺ \)[/tex].
So we can conclude that:
- HF and [tex]\( F^- \)[/tex] form a conjugate acid-base pair since HF loses an H⁺ to become [tex]\( F^- \)[/tex].
The correct answer is:
[tex]\[ \text{HF and } F^- \][/tex]
