What is the conjugate acid of HS-?
A. S-
B. H2S
C. HS-
D. S2-
The correct answer and explanation is:
The correct answer is B. H₂S.
To understand this, we need to know the concept of conjugate acids and conjugate bases. A conjugate acid is formed when a base gains a proton (H⁺), and a conjugate base is formed when an acid loses a proton.
In this case, HS⁻ is the conjugate base of H₂S. When HS⁻ gains a proton (H⁺), it becomes H₂S. So, H₂S is the conjugate acid of HS⁻.
Here’s a breakdown of the process:
- HS⁻ is a base because it has the ability to accept a proton.
- When HS⁻ accepts a proton (H⁺), the result is H₂S, which is an acid because it can donate a proton in further reactions.
It’s important to distinguish this from the other options:
- A. S²⁻: This is the conjugate base of HS⁻. It would be formed if HS⁻ loses a proton, not gains one.
- C. HS⁻: This is the base we started with, so it cannot be its own conjugate acid.
- D. S²⁻: This is again the conjugate base of HS⁻ and is not relevant here.
In summary, HS⁻ acts as a base, and its conjugate acid is H₂S. The conjugate acid of a base is always one proton (H⁺) more than the base itself, and that’s why H₂S is the correct answer.