Chapter 4

Question 1

Lewis acid

Answer 1

Electron acceptor, donates proton

Question 2

Lewis base

Answer 2

Electron donor , accepts proton

Question 3

What is the formula to calculate the Ka or acid dissociation constant ?

Answer 3

Ka = [H][A-]/[HA]

Question 4

What is the formula to calculate pKa ?

Answer 4

pKa=-logKa

Question 5

Does a stronger acid have a higher or lower pKa ?

Answer 5

Lower

Question 6

What are some functional groups that act as acids ?

Answer 6

Alcohols, aldehydes , ketones, carboxylic acid and carboxylic acid derivatives

Question 7

What are some functional groups that act as a base ?

Answer 7

Amide and amine

Question 8

Nucleophiles

Answer 8

Donate electrons and are characterized as Lewis bases

Question 9

What factors make up a good nucleophile?

Answer 9

1. More negative charge
2. Less electronegative
3. Less bulky so it has less steric hinderance
4. Solvent is not protic

Question 10

In polar protic solvent , what is the pattern for nucleophilicity?

Answer 10

Nucleophilicity increases down the periodic table

Question 11

In polar aprotic solution, what is the pattern for nucleophilicity ?

Answer 11

In polar aprotic solution, nucleophilicity increases up the periodic table

Question 12

Examples of strong nucleophiles

Answer 12

HO-, RO-, CN-

Question 13

Examples of fair nucleophiles

Answer 13

N3-, NH3, RCO2-

Question 14

Examples of weak nucleophiles

Answer 14

H2O, ROH, RCOOH

Question 15

Electrophiles

Answer 15

Equivalent to Lewis acid

Question 16

Which functional groups are considered strong electrophiles ?

Answer 16

Anhydrides , carboxylic acid, ester and amide

Question 17

What are the strongest leaving groups ?

Answer 17

Conjugate base of the strongest acid make the strongest leaving groups

Question 18

What is an SN1 reaction ? What is the rate limiting step in the SN1 reaction ?

Answer 18

First the leaving group leaves and generates a positively charged carbocation. A nucleophile later takes the place of the leaving group. The rate limiting step is the first step

Question 19

In an SN1 reaction , why do we want the carbocation to be more substituted ?

Answer 19

More alkyl branches stabilize the carbocation

Question 20

What is an SN2 reaction ? What is the rate limiting step ?

Answer 20

When the nucleophile attacks at the same time as when the leaving group leaves and this causes the configuration to invert

The rate limiting step is the only step in the reaction which includes the substrate and nucleophile

Question 21

What makes an SN2 reaction more reactive ?

Answer 21

Less substituted carbon

Question 22

Oxidation state

Answer 22

Hypothetical charge an atom would have if all the bonds were completely ionic

Question 23

Oxidation

Answer 23

Lose electrons, increase number of bonds to oxygen or any other atom beside carbon or hydrogen

Question 24

Reduction

Answer 24

Gain electrons, increasing bonds to H

Question 25

Oxidizing agent

Answer 25

Accepts electrons from other species and is reduced

Question 26

What makes an oxidizing agent strong ? Provide some examples of strong oxidizing agent

Answer 26

High affinity for electrons and high oxidation state - it’s a metal with a lot of oxygen atoms

O2, O3, Cl2 , permanganate

Question 27

What characteristics make a reducing agent strong ? Provide some examples

Answer 27

Low electronegativity

Magnesium, aluminum, zinc

Question 28

What is the organization of functional groups from least to most oxidized functional groups ?

Answer 28

1. Alkanes
2. Alcohol, alkyl halide, amines
3. Aldehyde, ketone , imines
4. Carboxylic acid, anhydride, ester, amide
5. Carbondioxide

Question 29

Chemoselectivity

Answer 29

Preferential reaction of a functional group in the presence of another