Honors Chemistry 1 Chapter 17 Review Answers
What is a Reaction Mechanism? Give an example.
The step-by-step sequence of reactions by which the overall chemical change occurs
What is the slowest step in the mechanism named?
Rate Determining Step
What is an intermediate?
A substance that is made in one step of a reaction mechanism and used in another step
Where on the energy profile is the activated complex formed?
It is formed at the highest point of the curve.
What is an activated complex?
It is a transitional structure between the reactants and products.
What is the difference between the E for and exothermic reaction and an endothermic reaction?
The E for an exothermic reaction is negative and the E for an endothermic reaction is positive.
What is the activation energy?
The minimum energy required to transform the reactants into an activated complex
How is the value for E determined?
The E is the difference between the reactants and products.
What is chemical kinetics?
The area of chemistry that is concerned with reaction rates and reaction mechanisms
What is necessary for a collision to be effective?
The collision must have sufficient energy and the correct orientation.
Draw an energy profile for an exothermic reaction and one for an endothermic reaction.
ExothermicEndothermic
What is the difference between a homogeneous reaction and a heterogeneous reaction?
A homogeneous reaction has only one phase, but a heterogeneous reaction has two phases such as solid and gas or solid and liquid.
Which is the only rate influencing factor that cannot be adjusted?
The nature of the reactants
As temperature increases; reaction rateincreases.
Tell how each of the following affects the collisions: temperature, surface area, concentration and a catalyst.
Temperature affects the frequency and energy of collisions.
Surface area and concentration affects the frequency of collisions.
A catalyst affects the efficiency of the collisions.
As surface are increases; reaction rateincreases.
As concentration increases; reaction rateincreases.
What is a catalyst?
A substance that changes the rate of a chemical reaction without itself being permanently consumed
List some ways in which a catalyst might work.
Provides an alternative energy pathway or reaction mechanism
May form an alternative activated complex that requires a lower activation energy
What is the difference between an uncatalyzed path and a catalyzed path?
The activation energy could be lower and the path would get to products faster.
Try # 6 on Page 581.
a.Eforward = +80 kJ/mol
Ereverse = -80 kJ/mol
Ea = 100 kJ/mol
Ea' = 20 kJ/mol
b. Eforward = -40 kJ/mol
Ereverse = +40 kJ/mol
Ea = 20 kJ/mol
Ea′ = 60 kJ/mol
c.Eforward = +10 kJ/mol
Ereverse = -10 kJ/mol
Ea = 70 kJ/mol
Ea′ = 60 kJ/mol