Chapter 15, Problem 86QRT

Interpretation Introduction

Interpretation:

The mass of ammonium chloride required to prepare a buffer of $\text{pH}=\text{9}\text{.00}$ with $400\text{mL}$ of $0.93\text{M}$ ammonia solution has to be calculated.

Concept Introduction:

The buffer is a solution that resists any change in pH on addition of ${\text{H}}^{+}$ and ${\text{OH}}^{-}$.  An acidic buffer is made up of a weak acid and its salt.  A basic buffer is made up of a weak base and its salt.  The formula to calculate the $\text{pH}$ of the buffer is shown below.

  $\text{pH}=\text{p}{K}_{\text{a}}+\log \frac{\left[{\text{A}}^{-}\right]}{\left[\text{HA}\right]}$