# A 25.0-mL sample of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl. a What was the concentration of the original hydroxylamine solution? b What is the pH at the equivalence point? c Which indicators, bromphenol blue, methyl red, or phenolphthalein, should be used to detect the end point of the titration? Why?

### General Chemistry - Standalone boo...

11th Edition
Steven D. Gammon + 7 others
Publisher: Cengage Learning
ISBN: 9781305580343

### General Chemistry - Standalone boo...

11th Edition
Steven D. Gammon + 7 others
Publisher: Cengage Learning
ISBN: 9781305580343

#### Solutions

Chapter
Section
Chapter 16, Problem 16.123QP
Textbook Problem

## A 25.0-mL sample of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl. a What was the concentration of the original hydroxylamine solution? b What is the pH at the equivalence point? c Which indicators, bromphenol blue, methyl red, or phenolphthalein, should be used to detect the end point of the titration? Why?

Expert Solution

(a)

Interpretation Introduction

Interpretation:

A 25.0 mL of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl

The concentration of the original hydroxylamine solution has to be calculated

Concept Introduction:

Equivalence point:

The equivalence point in titration is the point where the amount of standard titrant solution (in moles) and the unknown concentration analyte solution (in moles) becomes equal.

In other words, the equivalence point is the point obtained in a titration once a stoichiometric amount of reactant has been added.

### Explanation of Solution

To Calculate: The concentration of the original hydroxylamine

Given data:

A 25.0 mL of hydroxylamine solution is titrated to the equivalence point with 35.8 mL of 0.150 M HCl

Concentration of original hydroxylamine:

At equivalence point, the moles of base equals the moles of acid.

Therefore,

MNH2OH×25.0 mL  = 0.150 M × 35

Expert Solution

(b)

Interpretation Introduction

Interpretation:

A 25.0 mL of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl

The pH at the equivalence point has to be calculated

Concept Introduction:

Equivalence point:

The equivalence point in titration is the point where the amount of standard titrant solution (in moles) and the unknown concentration analyte solution (in moles) becomes equal.

In other words, the equivalence point is the point obtained in a titration once a stoichiometric amount of reactant has been added.

Expert Solution

(c)

Interpretation Introduction

Interpretation:

A 25.0 mL of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl

Among the indicators bromophenol blue, methyl red or phenolphthalein, the indicator that can be used to detect the end point has to be explained.

Concept Introduction:

Equivalence point:

The equivalence point in titration is the point where the amount of standard titrant solution (in moles) and the unknown concentration analyte solution (in moles) becomes equal.

In other words, the equivalence point is the point obtained in a titration once a stoichiometric amount of reactant has been added.

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