Chapter 11, Problem 11.41P

(a)

Interpretation Introduction

Interpretation:

The color observed for cresol purple indicator at $pH$ value $1$ has to be identified.

Concept Introduction:

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.  We cannot see with naked eyes the completion of titration reaction – the titrant and the analyte becoming equal in stoichiometric proportion, hence we use a chemical compound called indicator which indicates the end of the reaction by color change.

The chemical compound which is used as indicator is capable of exhibiting different color in different $pH$ range.  The end point refers to the color change and indicates equivalence point has been reached.

(b)

Interpretation Introduction

Interpretation:

The color observed for cresol purple indicator at $pH$ value $2$ has to be identified.

Concept Introduction:

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.  We cannot see with naked eyes the completion of titration reaction – the titrant and the analyte becoming equal in stoichiometric proportion, hence we use a chemical compound called indicator called which indicates the end of the reaction by color change.

The chemical compound which is used as indicator is capable of exhibiting different color in different $pH$ range.  The end point refers to the color change and indicates equivalence point has been reached.

(c)

Interpretation Introduction

Interpretation:

The color observed for cresol purple indicator at $pH$ value $3$ has to be identified.

Concept Introduction:

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.  We cannot see with naked eyes the completion of titration reaction – the titrant and the analyte becoming equal in stoichiometric proportion, hence we use a chemical compound called indicator called which indicates the end of the reaction by color change.

The chemical compound which is used as indicator is capable of exhibiting different color in different $pH$ range.  The end point refers to the color change and indicates equivalence point has been reached.