Chapter 3, Problem 1P

1. a. How many hydrogens does an alkane with 17 carbons have?
2. b. How many carbons does an alkane with 74 hydrogens have?

Interpretation Introduction

Interpretation:

The number of hydrogen atoms should be identified in the alkanes with 17 carbons.

Concept introduction:

Any organic molecule can be named by using certain rules given by IUPAC (International Union for Pure and applied chemistry).  IUPAC name consists of three parts in major namely prefix suffix and root word.

Prefix represents the substituent present in the molecule and its position in the root name.

Suffix denotes the presence of functional group if any in the molecule.  It can be an alkene, alkyne, alcohol, carboxylic acid, alcohol etc.

Root word represents the longest continuous carbon skeleton of the organic molecule.

Answer to Problem 1P

The number of hydrogens atoms in alkanes with 17 carbons are $36$

Explanation of Solution

Analyzing for the statement (a):

Let us consider the following general molecular formula

There is 17 carbon atoms in an alkane

${\text{C}}_{\text{n}}{\text{H}}_{(\text{2n+2})}$

$\begin{array}{l}\text{It indicated for n=17}\\ \text{The (n) values substituted for above equation}\\ {\text{C}}_{\text{n}}{\text{H}}_{(\text{2n+2})}={\text{C}}_{17}{\text{H}}_{(\text{2(17)+2})}\\ ={\text{C}}_{17}{\text{H}}_{(34\text{+2})}\\ ={\text{C}}_{17}{\text{H}}_{36}\end{array}$

The numbers of hydrogen atoms are in (36)

Interpretation Introduction

Interpretation:

The number of carbon atoms should be identified in the alkanes with 74 hydrogens.

Concept introduction:

Any organic molecule can be named by using certain rules given by IUPAC (International Union for Pure and applied chemistry).  IUPAC name consists of three parts in major namely prefix suffix and root word.

Prefix represents the substituent present in the molecule and its position in the root name.

Suffix denotes the presence of functional group if any in the molecule.  It can be an alkene, alkyne, alcohol, carboxylic acid, alcohol etc.

Root word represents the longest continuous carbon skeleton of the organic molecule.

Answer to Problem 1P

The number of carbon atoms in alkane with 74 hydrogens in $36$

Explanation of Solution

Analyzing for the statement (a):

Let us consider the following general molecular formula

The numbers of hydrogen atoms are in (36)

  $\begin{array}{l}\text{The alkanes with 74 hydrogens have}\\ {\text{C}}_{\text{n}}{\text{H}}_{\text{(2n+2)}}{\text{= C}}_{\text{n}}{\text{H}}_{\text{74}}\\ \text{It indicated for 2n+2=74}\\ \text{n}\text{=}\frac{\text{74-2}}{\text{2}}\\ \text{=}\text{36}\end{array}$

Therefore, the number of carbon atom in this compound is $36$