Conjugate acid–base pairs Knowledge-Based Practice

Questions

1. 1.

   What is the conjugate base of the ammonium ion ($\text{NH}_4^+$)?

   • A) $\text{NH}_3$
   • B) $\text{NH}_2^-$
   • C) $\text{NH}_4\text{OH}$
   • D) $\text{NH}_3^+$
2. 2.

   What are the conjugate base and the conjugate acid of the amphiprotic water molecule ($\text{H}_2\text{O}$), respectively?

   • A) $\text{H}_3\text{O}^+$ and $\text{OH}^-$
   • B) $\text{OH}^-$ and $\text{O}^{2-}$
   • C) $\text{OH}^-$ and $\text{H}_3\text{O}^+$
   • D) $\text{O}^{2-}$ and $\text{H}_3\text{O}^+$
3. 3.

   In the Brønsted–Lowry acid–base reaction $\text{HSO}_3^-(aq) + \text{CN}^-(aq) \rightleftharpoons \text{SO}_3^{2-}(aq) + \text{HCN}(aq)$, which species is the conjugate acid of the cyanide ion ($\text{CN}^-$)?

   • A) $\text{HSO}_3^-$
   • B) $\text{SO}_3^{2-}$
   • C) $\text{H}_2\text{SO}_3$
   • D) $\text{HCN}$
4. 4.

   What is the conjugate acid of the hydrogen phosphate ion, $\text{HPO}_4^{2-}$?

   • A) $\text{PO}_4^{3-}$
   • B) $\text{H}_2\text{PO}_4^-$
   • C) $\text{H}_3\text{PO}_4$
   • D) $\text{H}_2\text{PO}_4^{2-}$
5. 5.

   According to the Brønsted–Lowry definition, which of the following chemical pairs constitutes a conjugate acid–base pair?

   • A) $\text{H}_2\text{SO}_4$ and $\text{SO}_4^{2-}$
   • B) $\text{H}_3\text{O}^+$ and $\text{OH}^-$
   • C) $\text{H}_2\text{PO}_4^-$ and $\text{HPO}_4^{2-}$
   • D) $\text{NH}_4^+$ and $\text{NH}_2^-$

Answers and step-by-step solutions appear after you finish the test.