Consider the reaction below.

[tex]\[ \text{HI} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{I}^- \][/tex]

Which is an acid-conjugate base pair?

A. HI and [tex]\(\text{H}_2\text{O}\)[/tex]

B. [tex]\(\text{H}_2\text{O}\)[/tex] and [tex]\(\text{H}_3\text{O}^+\)[/tex]

C. [tex]\(\text{H}_3\text{O}^+\)[/tex] and [tex]\(\text{I}^-\)[/tex]

D. HI and [tex]\(\text{I}^-\)[/tex]



Answer :

To identify the acid-conjugate base pair in the given reaction:
[tex]$ HI + H_2O \rightarrow H_3O^+ + I^- $[/tex]
we need to determine which species donates and accepts protons (H⁺).

1. An acid is a species that donates a proton.
2. A base is a species that accepts a proton.
3. The conjugate base is what remains after the acid donates its proton.
4. The conjugate acid is what is formed when the base accepts a proton.

Let's analyze each component of the reaction:

1. HI:
- HI donates a proton (H⁺) to become I⁻.
- In this case, HI is the acid because it donates a proton.
- I⁻ is the conjugate base, as it is what remains after HI donates the proton.

2. H₂O:
- H₂O accepts a proton to become H₃O⁺.
- H₂O is acting as a base here because it accepts a proton.
- H₃O⁺ is the conjugate acid as it is formed when H₂O accepts the proton.

Now, we look at the pairs:
- HI and I⁻ form an acid-conjugate base pair.
- H₂O and H₃O⁺ form another pair, but this is not in the list of options.

The correct acid-conjugate base pair from the given options is:

HI and I⁻