Question

In the reaction H2O + NH3 NH4 + + OH- (a) H2 O acts as an acid towards NH3 (b) NH3 acts as acid towards H2O (c) H2O is the conjugate base of OH- (d) NH3 is the conjugate acid of NH4 +​

Answer 1

Explanation:

A conjugate acid-base pair differs by a single proton.

A conjugate acid is formed when a proton is accepted by a Bronsted base, while a conjugate base is formed when a proton is donated by a Bronsted acid.

The reaction is given below:

NH

3

+H

2

O→NH

4

+

+OH

−

Here, we have two conjugate acid-base pairs. They are as follows:

1. NH

4

+

and NH

3

2. H

2

O and OH

−

Answer 2

In the reaction $\[{H_2}O + N{H_3} \to N{H_4}^ + + O{H^ - }\]$, $\[{H_2}O\]$ acts as an acid towards $\[N{H_3}\]$. Thus, the correct option is (a).

Explanation:

• When a base accepts a proton, the species formed is known as the conjugate acid.
• On the other hand, when an acid loses a proton, the species formed is known as a conjugate base.
• In the given reaction, $\[{H_2}O + N{H_3} \to N{H_4}^ + + O{H^ - }\]$, $\[{H_2}O\]$ is acid and $\[N{H_3}\]$ is base.
• $\[N{H_4}^ + \]$ acts as the conjugate acid of $\[N{H_3}\]$ while $\[O{H^ - }\]$ acts as the conjugate base of $\[{H_2}O\]$.
• Therefore, the correct option is $\[{H_2}O\]$ acts as an acid towards $\[N{H_3}\]$.