Question

Consider the equilibrium reaction:
$N{H}_3+H_{2}O\rightleftharpoons N{H}_4^{+}+O{H}^{-}$
Which of the following species can act as a Bronsted-Lowry acid?

• A. Both (b) and (c)
• B. $N{H}_3$
• C. $N{H}_4^{+}$
• D. $H_{2}O$

Answer 1

Answer: (A)

The correct option is D Both (b) and (c)
Bronsted Lowry’s Concept :
Bronsted acid - species (molecule or ion) which has a tendency to donate a proton.
Bronsted base - species (molecule or ion) which has a tendency to accept a proton.
In the forward reaction, we can see that, $H_{2}O$ donates a proton $\left(H^{+}\right)$ to $N{H}_3$ and hence $N{H}_4^{+}$ is formed.
For the backward reaction, $N{H}_4^{+}$ donates a proton to act as Bronsted Lowry acid.
So here, $H_{2}O$ and $N{H}_4^{+}$ both acts as Bronsted -Lowry acids.