Chapter 24, Problem 24.16P

a)

Interpretation Introduction

Interpretation:

The Kovats retention index for the unknown has to be calculated.

Concept Introduction:

Kovats retention index:

Retention index, I for linear alkane equals 100 times the number of Carbon atoms.

For a molecule of Octane, $\text{I=800}$

For a molecule of Nonane, $\text{I=900}$

The elution of compound between Octane and Nonane will have retention index between 800 and 900 is calculated using the formula,

$\text{I=100}\left[\text{n+}\left(\text{N-n}\right)\frac{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{unknown}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}\right]$

Where, $\text{n}$= number of Carbon atoms in smaller alkane

$\text{N}$ = number of Carbon atoms in larger alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)$ = adjusted retention time of smaller alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)$ = adjusted retention time of larger alkane

To calculate the Kovats retention index for the unknown

b)

Interpretation Introduction

Interpretation:

The Kovats retention index for the unknown has to be given if the phase ratio of the column were doubled.

Concept Introduction:

Kovats retention index:

Retention index, I for linear alkane equals 100 times the number of Carbon atoms.

For a molecule of Octane, $\text{I=800}$

For a molecule of Nonane, $\text{I=900}$

The elution of compound between Octane and Nonane will have retention index between 800 and 900 is calculated using the formula,

$\text{I=100}\left[\text{n+}\left(\text{N-n}\right)\frac{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{unknown}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}\right]$

Where, $\text{n}$= number of Carbon atoms in smaller alkane

$\text{N}$ = number of Carbon atoms in larger alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)$ = adjusted retention time of smaller alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)$ = adjusted retention time of larger alkane

To give the Kovats retention index for the unknown if the phase ratio of the column were doubled

c)

Interpretation Introduction

Interpretation:

The Kovats retention index for the unknown has to be given if the length of the column were halved.

Concept Introduction:

Kovats retention index:

Retention index, I for linear alkane equals 100 times the number of Carbon atoms.

For a molecule of Octane, $\text{I=800}$

For a molecule of Nonane, $\text{I=900}$

The elution of compound between Octane and Nonane will have retention index between 800 and 900 is calculated using the formula,

$\text{I=100}\left[\text{n+}\left(\text{N-n}\right)\frac{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{unknown}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}{\text{log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)\text{-log}{\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)}\right]$

Where, $\text{n}$= number of Carbon atoms in smaller alkane

$\text{N}$ = number of Carbon atoms in larger alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{n}\right)$ = adjusted retention time of smaller alkane

${\text{t}}_{\text{r}}{}^{\text{'}}\left(\text{N}\right)$ = adjusted retention time of larger alkane

To give the Kovats retention index for the unknown if the length of the column were halved