Kinetics

Question 1

What is kinetics: based on? Used suspects? Questions answered?

Answer 1

Time
k, rate
How feel/slow & what will [ ] be at t(time)

Question 2

General rates

Answer 2

Change in something/time
Change in position(distance)/time
Ex. mph, cm/s

Question 3

Chemical rates

Answer 3

Rate=🔺[species]/🔺t
Coeff=moles of a species in a rxn
(-) or (+) means conc. increasing or decreasing (respectively)

Question 4

Collision model

Answer 4

• species must collide in order to react
• not all collisions result in a reaction
  check notes for visual

Question 5

Factors that govern chemical rate

Answer 5

1. Concentration: as [react.]^, rate ^
2. Temperature: as T^, rate ^
3. Activation energy: as Ea^, rate v
4. Steric orientation: A^, rate v

Question 6

Arrhenius Equation

Answer 6

k=Ae^(-Ea/RT)
- R=8.314 J/kmol

[react]^= k(—), rate^
T^= k^, rate^
A^= k^, rate^
Ea^= kv, ratev

Question 7

Differential rate law

Answer 7

aA+bB -> cC+dD

Rate=k[A]^m*[B]^n

Question 8

What does the rate law tell us about the rds (what the order means)

Answer 8

The rate at which the reaction takes place, zero or first or second order, but overall rxn is third order

Question 9

Determining the rate law from an elementary mechanistic step

Answer 9

Coeff tell the order
The missing m and n

Question 10

Integrated rate law

Answer 10

• Zero, first and second order
• makes [react] to t

Question 11

Zeroth order

Answer 11

• [A]t=-kt+[A]o
• Rate of rxn doesn’t depend on [A]
  check notes for graph

Question 12

First order

Answer 12

• ln[A]t=-kt+ln[A]o
• rate depends on [A]
  check notes for graph

Question 13

Second order

Answer 13

• 1/[A]t=kt+1/[A]o
• rate really, really drops on [A]
  check notes for graph

Question 14

Relationship between the slope between the best fit line and the rate constant

Answer 14

• According to rxn, linear line and (-)/(+) direction determines the rate order

Question 15

Half-life

Answer 15

• Times it takes for 1/2 of reactants to be consumed
  1. t1/2=50%
  2. t1/2=25%
  3. t1/2=12.5%

Question 16

Half life of first order reaction

Answer 16

ln[A]t=-kt+ln[A]o
ln[A]t-ln[A]o=-kt
ln([A]t1/2/ln[A)o)=-kt1/2
ln(1/2[A]o/[A]o)=-kt1/2
ln(1/2)/-k=t1/2
- only for first order

Question 17

Rxn coordinate diagrams

Answer 17

• exothermic rxn: react>prod neg change H
• endothermic rxn: react<prod pos change H

Question 18

Intermediate species

Answer 18

• species made in the middle of rxns
• ex. AC is the intermediate species in the following:
  A+BC->AC+B
  AC+D->A+CD

Question 19

Activated complex

Answer 19

• an unstable species created at the peak of a rxn
  check notes for example

Question 20

Activation energy (including the effect of a catalyst)

Answer 20

• amt of energy required for a rxn to take place
• catalysts lower this energy

Question 21

Catalysts effect on Activation energy

Answer 21

• lowers the energy amount used
  check notes for diagram

Question 22

Homogeneous catalyst

Answer 22

• same phase as reactants
• can be consumed in step 1 and regenerated in a subsequent step

Question 23

Heterogeneous catalyst

Answer 23

• different phase than reactants
• reactants are adsorbed onto surface of catalyst
• products are released