Chapter 11, Problem 11.35P

Interpretation Introduction

Interpretation:

A second derivative graph has to be plotted for the given titration data and the end point has to be found.

Concept introduction:

Acid-base titration is titration between acid and base. It is also known as neutralization reaction.

There are primarily four types of acid-base titrations –

• Strong base vs strong acid
• Strong base vs weak acid
• Weak base vs strong acid
• Weak base vs weak acid

Equivalence point ensures the titration reaction becomes completed and at this point the number of moles of titrant and the number of moles of analyte remain equal.  The end point refers to the color change and indicates equivalence point has been reached.

In a graph, representing two functions, second derivative corresponds to the concavity of the graph.  In a second derivative titration graph the point at which the concavity of the graph changes is referred to equivalence point.

Titration curve is plotted for volume of the titrant versus $pH$ calculated.  Thus in titration calculations, the first derivative corresponds to $\Delta pH/\Delta mL$ and the first derivative graph is plotted as volume of acid versus $\Delta pH/\Delta mL$.  The second derivative corresponds to $\frac{\Delta \left(\Delta pH/\Delta mL\right)}{\Delta mL}$ and the second derivative graph is plotted as volume of acid versus $\frac{\Delta \left(\Delta pH/\Delta mL\right)}{\Delta mL}$.