# 2.E: Polar Covalent Bonds; Acids and Bases (Exercises)


These are the homework exercises to accompany the Textmap for McMurry's Organic Chemistry textbook.

## 2.1 Polar Covalent Bonds: Electronegativity

### 2.1 Exercises

#### Questions

Q2.1.1

Rank the following from least polar to most polar using knowledge of electronegativity

CH3CH2-Li CH3CH2-K CH3CH2-F CH3CH2-OH

#### Solutions

S2.1.1

(least polar) OH < F < Li < K (most polar)

## 2.2 Polar Covalent Bonds: Dipole Moments

### 2.2 Exercises

#### Questions

Q2.2.1

The following molecule has no dipole moment in the molecule itself, explain.

Q2.2.2

Which of the following molecules has a net dipole?

Q2.2.3

Within reactions with carbonyls, such as a reduction reaction, the carbonyl is attacked from the carbon side and not the oxygen side. Using knowledge of electronegativity explain why this happens.

#### Solutions

S2.2.1

The hydroxyl groups are oriented opposite of one another and therefore the dipole moments would “cancel” one another out. Therefore having a zero net-dipole.

S2.2.2

1, 3, and 4 have a net dipoles.

S2.2.3

The oxygen is more electronegative than the carbon and therefore creates a dipole along the bond. This leads to having a partial positive charge on the carbon and the reduction can take place.

## 2.3: Formal Charges

### 2.3 Exercises

#### Questions

Q2.3.1

Give the formal charges for all non-hydrogen atoms in the following molecules: $$\ce{BH4^{-}}$$, $$\ce{H2O}$$, $$\ce{CH3O^{-}}$$

#### Solutions

S2.3.1

BH4 (B = −1)

H2O (O = 0)

CH3O (C = 0, O = −1)

## 2.4 Resonance

### 2.4 Exercises

#### Questions

Q2.4.1

Draw the resonance structures for the following molecule:

S2.4.1

## 2.5 Rules for Resonance Forms

### 2.5 Exercises

#### Questions

Q2.5.1

Are all the bond lengths the same in the carbonate ion, CO32-?

#### Solutions

S2.5.1  Yes, the bond lengths in carbonate ion are all the same.  Carbonate ion exists as the resonance hybrid of the three resonance forms below.

## 2.7 Acids and Bases: The Brønsted-Lowry Definition

### 2.7 Exercises

#### Questions

Q2.7.1

Is the following molecule a Brønsted acid or base?

HSO4

#### Solutions

S2.7.1

It can be both, consider the following schemes:

## 2.9 Predicting Acid-Base Reactions from pKaKa Values

### 2.9 Exercises

#### Questions

Q2.9.1

In the following reactions give the resulting products and label the conjugate acid and bases.

S2.9.1

## 2.10 Organic Acids and Organic Bases

### 2.10 Exercises

#### Questions

Q2.10.1

Determine which of the one of the molecules is an acid or a base.

S2.10.1

1 = Base

2 = Acid

3 = Acid

4 = Acid

## 2.11 Acids and Bases: The Lewis Definition

### 2.11 Exercises

#### Questions

Q2.11.1

For the following molecules state wither they are Lewis acid or base and wither or not they are a Brønsted acid or base.

#### Solutions

S2.11.1

Acetone is a Lewis base and a Brønsted base. Ammonium cation is both a Lewis acid and a weak Brønsted acid.

## 2.13 Molecular Models

2.E: Polar Covalent Bonds; Acids and Bases (Exercises) is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.