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ChemistryPrinciples of Instrumental Analysis(a) Interpretation: An equation that relates the desired quantity, mass S 2 - (ng), to the chloridometer readout in mass Cl- (ng) should be derived. Concept introduction: Chloridometer is used in chlorine determination. The number of moles of chloride in an unknown solution can be determined by the following equation. ( n C l − ) u = t u t s × ( n C l − ) s ( n C l − ) u = number of moles of chloride in the unknown sample ( n C l − ) s = number of moles of chloride in the standard sample t u = time required to titrate the unknown chloride solution t s = time required to titrate the standard chloride solutionStart your trial now! First week only $4.99!*arrow_forward*

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7th Edition

Douglas A. Skoog + 2 others

Publisher: Cengage Learning

ISBN: 9781305577213

Chapter 24, Problem 24.13QAP

Interpretation Introduction

**(a)**

**Interpretation:**

An equation that relates the desired quantity, mass S^{2}- (ng), to the chloridometer readout in mass Cl- (ng) should be derived.

**Concept introduction:**

Chloridometer is used in chlorine determination. The number of moles of chloride in an unknown solution can be determined by the following equation.

Interpretation Introduction

**(b)**

**Interpretation:**

Total charge in coulombs required to generate the Ag+ needed to precipitate the sulfide in the standard should be determined.

**Concept introduction:**

The number of moles can be calculated from mass and molar mass as follows:

Here, m is mass and M is molar mass.

Charge of 1 mole of electron transferred = 96485 C

Interpretation Introduction

**(c)**

**Interpretation:**

Each of the chloride results should be converted to mass S^{2}- (ng)

**Concept introduction:**

The number of moles can be calculated from mass and molar mass as follows:

Here, m is mass and M is molar mass.

Interpretation Introduction

**(d)**

**Interpretation:**

The average mass of S^{2-}, standard deviation, and the % RSD of each standard should be determined.

**Concept introduction:**

The mean value for mass can be calculated as follows:

The standard deviation can be calculated as follows:

The value of % RSD can be calculated as follows:

Here, s is a standard deviation and

Interpretation Introduction

**(e)**

**Interpretation:**

A plot of the average mass of S^{2}- determined (ng) versus the actual mass (ng) should be prepared. Slope, intercept and standard error and R^{2} value should be determined.

**Concept introduction:**

In the plot,

X-axis = actual mass of S^{2}-

Y-axis = determined mass of S^{2}-

Interpretation Introduction

**(f)**

**Interpretation:**

The detection limit (ng) and in parts per million using a k factor of 2 should be determined.

**Concept introduction:**

The minimum distinguishable analytical signal can be calculated as follows:

Here,

k − constant

Interpretation Introduction

**(g)**

**Interpretation:**

Mass of S^{2}- (ng) in an unknown sample should be determined. The concentration of S^{2}- in parts per million should be determined.

**Concept introduction:**

The number of moles can be calculated from mass and molar mass as follows:

Here, m is mass and M is molar mass.

The concentration can be calculated as follows:

Here, n is the number of moles and V is volume.