Chapter 6

Question 1

Concerted reaction?

Answer 1

one step reaction, no intermediates

Question 2

Stepwise reaction?

Answer 2

two step, intermediates involved

Question 3

Homolysis?

Answer 3

homolytic cleavage, one electron goes to each atom

Question 4

Heterolysis?

Answer 4

heterolytic cleavage, electrons divided unequally they go to electronegative atom, form charged intermediates

Question 5

Bond dissociation energy?

Answer 5

amount of energy required to homolytically cleave a bond, delta H (+) is endothermic

Question 6

What happens to bond strength as you go across PT?

Answer 6

increases

Question 7

What happens to bond strength as you go down PT?

Answer 7

decreases

Question 8

Keq > 1?

Answer 8

favorable equilibrium, -G, to the right, more products

Question 9

Keq

Answer 9

unfavorable equilibrium, +G, to the left, more reactants

Question 10

Equation for delta G not?

Answer 10

G= -RTlnK

Question 11

A small difference in free energy equals ?

Answer 11

a large difference in products vs reactants

Question 12

Is more disorder favorable or unfavorable?

Answer 12

favorable

Question 13

In most reactions delta S is _____ so G = ____.

Answer 13

negligible

H

Question 14

What are two cases where S is not negligible?

Answer 14

1. Fragmentations (AB –> A + B) = S is +, favorable

2. Cyclizations- ring is formed, unfavorable, more order, S is negative

Question 15

Transition state?

Answer 15

energy max peak on diagram, not an intermediate, not isolated or observed

Question 16

Activation energy?

Answer 16

minimum amount of energy for the reaction to proceed

Ea is proportional to rxn rate

Question 17

Who developed transition state theory?

Answer 17

Henry Eyring

Question 18

When products are lower than reactants on an energy diagram, is it endo or exo?

Answer 18

exothermic

Question 19

When products are higher than reactants on an energy diagram, is it endo or exo?

Answer 19

endo

Question 20

How can you accelerate reactions?

Answer 20

1. increase rxn temp

2. increase concentration of reactants

Question 21

What happens to rate when you increase rxn temp by 10 degrees celsius?

Answer 21

rxn rate doubles

Question 22

What is the ideal Kcal/mol range for a reaction?

Answer 22

10-35

Question 23

Rate equation?

Answer 23

rate = k[reactants]

Question 24

What is the order of a reaction?

Answer 24

sum of exponents of concentration terms

Question 25

Catalyst?

Answer 25

substance that speeds up the rate of the reaction by lowering Ea and is not consumed, it is unchanged

• stabilizes transition state
• enzymes
• dont change Eq

Question 26

The higher the bond dissociation energy, the ______ the bond.

Answer 26

stronger

Question 27

The higher the Ea, the ____ the rate constant.

Answer 27

smaller

Question 28

Eq always favors the species that is ____ in energy.

Answer 28

lower

Question 29

Homolysis generates _______.

Answer 29

radicals with unpaired electrons

Question 30

Heterolysis generates _______.

Answer 30

ions

Question 31

Breaking bonds generates ______.

Answer 31

reactive intermediates

Question 32

Radicals are ______.

Answer 32

electrophilic

Question 33

Carbocations are ______.

Answer 33

electrophilic

Question 34

Carbanions are ______.

Answer 34

nucleophilic

Question 35

What does -H mean?

Answer 35

bonds in products are stronger than bonds in reactants