Identify the base-conjugate acid pair in this balanced equation:

[tex]\[ NH_3 + HNO_3 \rightarrow NH_4^{+} + NO_3^{-} \][/tex]

A. [tex]\( NH_3 / NH_4^{+} \)[/tex]

B. [tex]\( NH_3 / NO_3^{-} \)[/tex]

C. [tex]\( HNO_3 / NH_4^{+} \)[/tex]

D. [tex]\( HNO_3 / NO_3^{-} \)[/tex]



Answer :

To identify the base-conjugate acid pair in the given balanced equation, we need to understand the concept of acids and bases in the Bronsted-Lowry sense. According to the Bronsted-Lowry theory, an acid is a proton (H[tex]\(^+\)[/tex]) donor, and a base is a proton acceptor. A conjugate acid is formed when the base gains a proton, and a conjugate base is what remains after the acid has donated a proton.

The given equation is:
[tex]\[ NH_3 + HNO_3 \rightarrow NH_4^+ + NO_3^- \][/tex]

Let's analyze each component:

1. Identify the reactants and products:

- [tex]\( NH_3 \)[/tex] is ammonia.
- [tex]\( HNO_3 \)[/tex] is nitric acid.
- [tex]\( NH_4^+ \)[/tex] is the ammonium ion.
- [tex]\( NO_3^- \)[/tex] is the nitrate ion.

2. Determine proton transfer:

- [tex]\( NH_3 \)[/tex] becomes [tex]\( NH_4^+ \)[/tex]. This means [tex]\( NH_3 \)[/tex] accepts a proton (H[tex]\(^+\)[/tex]). Therefore, [tex]\( NH_3 \)[/tex] acts as a base, and [tex]\( NH_4^+ \)[/tex] is its conjugate acid.
- [tex]\( HNO_3 \)[/tex] becomes [tex]\( NO_3^- \)[/tex]. This means [tex]\( HNO_3 \)[/tex] donates a proton (H[tex]\(^+\)[/tex]). Therefore, [tex]\( HNO_3 \)[/tex] acts as an acid, and [tex]\( NO_3^- \)[/tex] is its conjugate base.

3. Match the pairs:

- The pair [tex]\( NH_3 \)[/tex] (base) and [tex]\( NH_4^+ \)[/tex] (conjugate acid) forms a base-conjugate acid pair.
- The pair [tex]\( HNO_3 \)[/tex] (acid) and [tex]\( NO_3^- \)[/tex] (conjugate base) forms an acid-conjugate base pair.

Therefore, the correct base-conjugate acid pair in the given balanced equation is:
[tex]\[ NH_3 / NH_4^+ \][/tex]