Chapter 18, Problem 1SAQ

A buffer is 0.100 M in NH₄CI and 0.100 M in NH₃. When a small amount of hydrobromic acid is added to this buffer, which buffer component neutralizes the added acid?

• Cl−
• NH₃
• NH₄+
• none of the above (Hydrobromc acid will not be neutralized by this buffer.)

Interpretation Introduction

Interpretation:

Buffer components which neutralizes the added acid should be determined.

Concept introduction:

A buffer solution contains a weak acid/base mixed with its conjugate base/acid and resists the change in pH.

Answer to Problem 1SAQ

Correct answer:

Option (b) is a correct answer.

Explanation of Solution

Reasons for the correct option: The given buffer is 0.100 M NH₄Cl and 0.100 M in NH₃. When small amount of hydrobromic acid, $\text{HBr}$ is added to this buffer which is the acid and it is neutralized by ammonia, a base. So, ${\text{NH}}_3{}^{}$ is a buffer component that neutralizes the added acid.

Reasons for the incorrect options: Option (a) is given as ${\text{Cl}}^{\text{-}}$ .So, this is a wrong option.

Option (c) is given as ${\text{NH}}_{\text{4}}{}^{\text{+}}$ . So, this is a wrong option.

Option (d) is given as none of the above. So, this is a wrong option.