Question

Which of the following is NOT a conjugate acid-base pair?

1) CH3COO- and CH3COOH
2) F- and HF
3) H₂O and H3O+
4) NH₃ and H3O+

Answer 1

The NOT a conjugate acid-base pair among the options provided is NH3 and H3O+ as they do not directly transform to each other by the gain or loss of a proton. The correct option is 4).

Step-by-step explanation:

The question asks which of the following is NOT a conjugate acid-base pair. A conjugate acid-base pair consists of two species that transform into each other by gain or loss of a proton (H+).

The pairs CH3COO-/CH3COOH, F-/HF, and H2O/H3O+ all embody this relationship. However, NH3 and H3O+ do not form a conjugate acid-base pair because they are not directly related through the gain or loss of a proton.

To further clarify, in each of the correct pairs:

• CH3COO- gains a proton to become CH3COOH.
• F- gains a proton to form HF.
• H2O gains a proton to become H3O+.

While NH3 can accept a proton to become NH4+ (its conjugate acid), H3O+ is not the result of NH3 accepting a proton and therefore is not its conjugate acid. Option 4) is the correct one.