Question

Identify the conjugate bases of \(\text{H}_3\text{PO}_3\) and \(\text{H}_2\text{SO}_4\) respectively from following.

• A. \(\text{HPO}_3^{2-}\) and \(\text{SO}_4^{2-}\)
• B. \(\text{HPO}_3^{2-}\) and \(\text{HSO}_4^-\)
• C. \(\text{H}_2\text{PO}_3^-\) and \(\text{HSO}_4^-\)
• D. \(\text{PO}_3^{3-}\) and \(\text{SO}_4^{2-}\)

Hint:

A conjugate base is formed by removing one proton, and H3PO3 is only dibasic.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
According to Bronsted-Lowry theory, the conjugate base of an acid is what remains after the acid loses exactly one proton (\(\text{H}^+\)).

Step 2: Key Formula or Approach:
\(\text{H}_3\text{PO}_3 \to \text{H}_2\text{PO}_3^- + \text{H}^+\) and \(\text{H}_2\text{SO}_4 \to \text{HSO}_4^- + \text{H}^+\).

Step 3: Detailed Explanation:
Removing one \(\text{H}^+\) from \(\text{H}_3\text{PO}_3\) gives \(\text{H}_2\text{PO}_3^-\).
Removing one \(\text{H}^+\) from \(\text{H}_2\text{SO}_4\) gives \(\text{HSO}_4^-\).
Options A, B and D contain species that have lost two or three protons, such as \(\text{SO}_4^{2-}\) or \(\text{HPO}_3^{2-}\), or that pair a correct base with a wrong one. A conjugate base differs from its acid by just one proton.

Final Answer:
The conjugate bases are \(\text{H}_2\text{PO}_3^-\) and \(\text{HSO}_4^-\), option (C). \[ \boxed{\text{H}_2\text{PO}_3^- \text{ and } \text{HSO}_4^-} \]