Chapter 16, Problem 1SAQ

Interpretation Introduction

Introduction: A buffer contains a significant amount of either weak acid and its conjugate base or a weak base and its conjugate acid. When the additional base is added to a buffer, the weak acid reacts with the base, which neutralizes it. When acid is added to a buffer, the conjugate base reacts with the acid, which neutralizes it. In this way, a buffer can maintain a nearly constant pH.

Answer to Problem 1SAQ

Correct answer: (c) $N{H}_3$

Explanation of Solution

In the given buffer of 0.100 M in $N{H}_{4}Cl$ and 0.100 M in $N{H}_3$, $N{H}_3$ is weak base and $N{H}_{4}Cl$ is a conjugate acid of $N{H}_3$. When a small amount of hydrobromic acid, $HBr$ is added to this buffer, $N{H}_3$ (a weak base) neutralizes the added acid HBr. The equation for this neutralization is as follows:

$N{H}_3+H^{+}\to N{H}_4^{+}$

Conclusion

Hence, the correct option is (c).