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Which of the following is a conjugate acid-base pair?

A) OH, H₂O
B) NH₃, OH
C) OH, NH₂
D) H₂O, NH₄

User Lukas S
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1 Answer

4 votes

Final answer:

The correct conjugate acid-base pair is H₂O and NH₄⁺, where H₂O is the acid that donates a proton to form its conjugate base OH⁻, and NH₃ accepts a proton to form its conjugate acid NH₄⁺.

Step-by-step explanation:

The correct conjugate acid-base pair from the provided options is D) H₂O, NH₄⁺. In Bronsted-Lowry acid-base theory, acids are proton donors and bases are proton acceptors. A conjugate acid-base pair consists of two species that differ by the presence or absence of a hydrogen ion (H⁺). Therefore, when H₂O (acting as an acid) donates a proton, it forms its conjugate base OH⁻. Similarly, NH₃ (acting as a base) accepts a proton to form its conjugate acid NH₄⁺. This relationship is evident in the reaction between water and ammonia, which illustrates these conjugate pairs as H₂O (acid) and OH⁻ (conjugate base), as well as NH₃ (base) and NH₄⁺ (conjugate acid).

One pair is H₂O and OH, where H₂O has one more H* and is the conjugate acid, while OH¯ has one less H* and is the conjugate base. The other pair consists of (CH3)3N and (CH3)3NH*, where (CH3)3NH* is the conjugate acid (it has an additional proton) and (CH3)3N is the conjugate base.

User Charles Zink
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