Chapter U2.9, Problem 4E

Interpretation Introduction

(a)

Interpretation:

Lewis dot structure of the given carboxylic acid molecule must be drawn.

Concept introduction:

Lewis dot structure is the representation of molecule in which valence electrons are shown as dots.

Answer to Problem 4E

Lewis structure of the given carboxylic is shown below.

Explanation of Solution

Each carbon has four valencies. The oxygen atoms has valency two. There are two lone pairs on each O atom. Each atom is octet fulfilled except hydrogen atoms which are duplet (having 2 electrons).

Interpretation Introduction

(b)

Interpretation:

Structural formula of the given carboxylic acid must be drawn.

Concept introduction:

Structural formula is the representation of a molecule in which the arrangements of all the atoms are shown.

Answer to Problem 4E

Structural formula of the given carboxylic acid (heptanoic acid) is shown below.

Explanation of Solution

Structural formula of heptanoic acid is drawn in which all the carbon atoms have 4 bonds. Each O has two bonds and two lone pairs of electrons. There is no lone pair on C and H atoms. Hydrogen atoms of the carbon chain are not shown to avoid complexity of the structure.

Interpretation Introduction

(c)

Interpretation:

The functional group of the given molecule must be predicted.

Concept introduction:

Functional groups are atoms or group of atoms which controls the physical and chemical properties of the molecule.

Answer to Problem 4E

There is carboxylic acid functional group in the given molecule.

Explanation of Solution

The functional group (COOH) present in heptanoic acid is shown in red. In this, one carbon is double bonded with one O and single bonded with another OH group.

Interpretation Introduction

(d)

Interpretation:

The smell and name of the given molecule must be predicted.

Concept introduction:

Organic molecule can be named easily following the IUPAC (International Union of Pure and applied Chemistry) nomenclature system. Trivial name is also there for organic molecule. Smell sometimes depends on the class of the molecule.

Answer to Problem 4E

Name of the molecule is heptanoic acid as per IUPAC system. Trivial name is enanthic acid. It has smell of rancid oil.

Explanation of Solution

Numbering of the carbon chain is done by giving priority (number 1) to the functional group (COOH) bearing C. Total carbon is 7. So the IUPAC name is heptanoic acid. It is named as enanthic acid in trivial naming system.

The smells of this compound is like rancid oil.