Chapter 9, Problem 9.18P

(a)

Interpretation Introduction

Interpretation:

Whether $\text{NaOH}$ or $\text{HCl}$ is added to $\text{HEPES}$ to bring its $\text{pH}$ to 7.45 has to be determined.

Concept Introduction:

$\text{pH}$ of solution helps to determine the concentration of hydrogen ions in a solution. It explains the acidity and basicity of a solution. $\text{pH}$ value less than 7 indicates acidity and more that 7 indicates basicity. If $\text{pH}$ value is equal to 7 solution is neutral.

(b)

Interpretation Introduction

Interpretation:

Preparation of $\text{HEPES}$ at $\text{pH}$ equals to 7.45 has to be determined.

Concept Introduction:

Concentration of a solution is expressed by molarity and is denoted by $M$. It is defined as the ratio of number of moles of solute to volume of solution in $1\text{ L}$.

The formula to calculate moles is as follows:

  $\text{Moles}=\frac{\text{mass of solute}}{\text{molar mass of solute}}$

The formula used to calculate concentration is as follows:

  $\text{Concentration}=\frac{\text{moles}}{\text{volume of solution}\left(\text{L}\right)}$