Chapter 13 - Conceptual Questions

Question 1

What is the linear graph for a zero order equation?

Answer 1

Question 2

What is the linear graph for a first order equation?

Answer 2

Question 3

What is the linear graph for a second order equation?

Answer 3

Question 4

Identify the order with respect to the reactant, A.

(A—–> products)

The half-life of A is independent of the initial concentration of [A]

Answer 4

1

Question 5

Identify the order with respect to the reactant, A.

(A —–> products)

      A twofold increase in the initial concentration of A leads to a fourfold increase in the initial rate.

Answer 5

2

Question 6

Identify the order with respect to the reactant, A.

(A —–> products)

         A twofold increase in the intial cocentration of A                  .leads to a 1.41-fold increase in the intial rate.

Answer 6

.5

Question 7

Identify the order with respect to the reactant, A.

                                  (A-----\> products)

The time required for [A] to decrease from [A]₀ to [A]₀/2 is equal to the time required for [A] to decrease from [A]_o/2 to [A]_o/4

Answer 7

1

Question 8

Identify the order with respect to the reactant, A.

                                   (A-----\> products)

The decrease of [A] is constant

Answer 8

0

Question 9

What is a catalyst?

Answer 9

• Consumed then reformed
• • A catalyst provides an alternative route for the reaction with a lower activation energy.
• It does not “lower the activation energy of the reaction”

.

Question 10

What is an intermediate?

Answer 10

An intermediate is a sustance which is formed, then consumed in a reaction mechanism.

Question 11

number of particles vs. energy

(graph)

Answer 11

Question 12

Label the energy diagram from a two-step reaction

Answer 12

Question 13

How do energy diagrams for un-catalyzed and catalyzed reactions differ? (graph)

Answer 13

Question 14

In a reaction mechanism, which reaction determines the rate law?

Answer 14

In a reaction mechanism, the reaction that requires the most energy is the rate-determining step.

(the slow reaction)

Question 15

What is an “elementary reaction”?

Answer 15

An elementary reaction represents, at the molecular level, a single stage in the progress of the overall reaction.

Their coefficients will be their order in the rate law

Question 16

What is molecularity in elementary reactions?

Answer 16

The molecularity of an elementary reaction refers to the number of free atoms, ions, or molecules that react.

unimoleluar reaction – an elementary reaction that involves one reactant molecul

bimolecular reaction - an elementary reaction that involves two reactant molecules

termolecular reaction - an elementary reaction that involves three reactant molecules

Question 17

How do you determine the overall stoichiometry if given a mechanism

Answer 17

1) Add all the products of each elementary step then all the reactants into one giant equation (Hess’s Law)
2) Then remove the intermediates, which are molecules that are formed and consumed in the reaction.
3) Balance the reaction

Question 18

What is the “rate determining step” (RDS) and how is it related to the overall law?

Answer 18

It is the slow elementary reaction of mechanism.
The elementary reaction can be used to determine the overall law from coefficient, unless intermediates are included, then you’ll have to do some algebra.

Question 19

How does temperature affect the rate constant k?

Answer 19

Rate constant increases exponentially with temperature.

Question 20

What is the Arrhenious Equation?

Answer 20

Question 21

How does activation energy relate to the rate constant?

Answer 21

As activation energy goes up (E_a), rate constant goes down (k)

Question 22

What is the equation for Beer’s Law?

Answer 22