Kinetics

Question 1

Requirements for collision to result in a reaction

Answer 1

1) sufficient collision energy to meet activation energy
2) correct collision orientation

Question 2

Activation energy is

Answer 2

collision energy to break bonds and produce a reaction.

Question 3

Graphically, activation energy is

Answer 3

the energy from the reactants to the top of the hill.

Question 4

When looking at an elementary step, the rate law can be determined from

Answer 4

the coefficients

Question 5

Rate constant (k) units formula

Answer 5

M^1-n • time^-1

Question 6

Graph to linearize 0th order

Answer 6

[concentration] vs. time
Slope equals –k

Question 7

Graph to linearize 1st order

Answer 7

ln[concentration] vs. time
Slope equals –k

Question 8

Graph to linearize 2nd order

Answer 8

1/[concentration] vs. time
Slope equals k

Question 9

Ways to speed up reaction

Answer 9

1) Increase reactant concentration (increases number of collisions unless 0th order)

2) Add catalyst (lowers activation energy)

3) Increase surface area of solid (increases number of collisions)

4) Decrease volume of gas to increase pressure (increases number of collisions)

5) Increase temperature (increases number of collisions AND collision energy)

Question 10

Catalysts lower activation energy by

Answer 10

providing a different reaction mechanism.

Note: Catalysts are NEVER consumed in the overall reaction. They are used in an early step and remade in a later step.

Question 11

Nuclear decay of radioisotopes follows __________ order kinetics.

Answer 11

1st

Question 12

Reaction order with a constant half-life

Answer 12

1st

Question 13

Greater activation energies correspond to _________ reactions.

Answer 13

Slower

Question 14

On a reaction energy diagram, the ___________ hill represents the slowest step.

Answer 14

Tallest

Question 15

Which elementary step in a reaction mechanism determines the rate law?

Answer 15

Slowest step/rate-determining step

Question 16

How do you determine the rate law of a reaction based on a reaction mechanism?

Answer 16

Coefficients of slowest elementary step

Question 17

Intermediates ________ in an early step and _______ in a later step.

Answer 17

made: used

Question 18

The concentrations of intermediates are usually

Answer 18

Extremely low due to instability

Question 19

What do we generally try to remove from a rate law based on a reaction mechanism?

Answer 19

Intermediates

Question 20

How do we remove an intermediate from a rate law?

Answer 20

Use a previous fast equilibrium/fast reversible step

Question 21

Catalysts are _______ in an early step and ______ in a later step.

Answer 21

Used: made

Question 22

Catalysts ___________ be used in a rate law.

Answer 22

CAN