Question

Identify conjugate acid-base pair from following equilibrium reaction.
$\text{HSO}_{3(\text{aq})}^- + \text{H}_3\text{O}_{(\text{aq})}^+ \rightleftharpoons \text{H}_2\text{SO}_3 + \text{H}_2\text{O}$

• A. $\text{H}_2\text{SO}_3$ and $\text{HSO}_3^-$
• B. $\text{HSO}_3^-$ and $\text{H}_3\text{O}^+$
• C. $\text{H}_2\text{SO}_3$ and $\text{H}_2\text{O}$
• D. $\text{H}_3\text{O}^+$ and $\text{H}_2\text{SO}_3$

Hint:

Acid $\xrightarrow{-H^+}$ Conjugate Base; Base $\xrightarrow{+H^+}$ Conjugate Acid.

Answer 1

The Correct Option is A

Step 1: Concept
A conjugate acid-base pair consists of two substances that differ only by one proton ($H^+$).
Step 2: Analysis
In the given reaction: - $\text{HSO}_3^-$ accepts a proton to become $\text{H}_2\text{SO}_3$. Thus, $\text{HSO}_3^-$ is the base and $\text{H}_2\text{SO}_3$ is its conjugate acid. - $\text{H}_3\text{O}^+$ loses a proton to become $\text{H}_2\text{O}$. Thus, $\text{H}_3\text{O}^+$ is the acid and $\text{H}_2\text{O}$ is its conjugate base.
Step 3: Conclusion
The pair $\text{H}_2\text{SO}_3$ and $\text{HSO}_3^-$ differ by exactly one $H^+$.
Final Answer: (A)