HChem Chemical Kinetics Test Flashcards Preview

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Flashcards in HChem Chemical Kinetics Test Deck (36):
1

The enthalpy change is the _____ of the reaction and is found by ____________

Heat
Products-reactants

2

The activation energy=

Activated complex-reactants

3

Enthalpy changed and activation energy have what unit?

In

4

The strongest bonds are where the _____ energy is greatest

Kinetic (potential energy is weakest)

5

The weakest bonds are where the ____ energy is strongest

Potential (kinetic is weakest)

6

Why are bonds with greater potential energy weaker

They are closer to the activated complex and it takes less force to break the bonds

7

As reactant molecules approach each other, they exert ________ forces on each other. Thus, as they move together, their speed ___________ and their potential energy __________

Repulsive, goes down, goes up

8

What is the activated complex

The intermediate created at the peak of the reaction

9

What is the activation energy

The energy required to break the bonds/ minimum quantity of energy that the reacting species must possess in order to undergo a reaction

10

What two requirements must be met before a collision between two reactant particles is effective

Must collide with high energy (greater of equal than Ea)
Must hit each other with the correct orientation

11

A slow reaction would start with a ______ PE

High

12

The activated complex of a step is represented by the ____ while the intermediate is represented by the __________

Peak, valley at the bottom

13

Would you expect a reaction with 5 particles to take place in one step

No- they won't collide at the right speed and orientation the first try

14

Adding a catalyst to any step but the RDS will/will not affect the reaction rate

Will not

15

If a catalyst is discovered that increases the rate of the RDS, how will the overall reaction be affected

It will increase

16

The RDS has the _____ peak

Highest

17

The sum of your elementary step will equal the ______ reaction

Overall

18

How do you know which of two fast steps will be faster

Check for intermediates

19

A catalyzed reaction will ____ at the same place but have a smaller ___________

Begin, activation energy (shorter peak)

20

Doubling the concentration of ClO- quadruples the initial rate of formation of ClO3-
How would you write the rate expression

2^x=4
X=4
R=k[ClO-]^2

21

Be sure to check the ______ in scientific notation to make sure it is negative/positive

Exponent

22

Check the unit in the box for __________ to know what it should be in the answer

Reaction rate (usually M/s)

23

If volume decreases, equilibrium will shift towards the side with _____ moles

Less

24

Intermediates may not appear in _________, but sometimes they have a substitute in the mechanism

Reaction rates

25

Catalysts are __________ in an early step in the mechanism an a ________ in a later step

Reactant, product

26

Increasing the volume of system will shift the equilibrium towards the side with _____ moles of gas

More

27

Decreasing the volume of a system will shift the equilibrium to the side with _______ moles of gas

Less

28

When is a reaction at equilibrium

Rate of formation on one side=one of formation on the other

29

If forward direction was favored, you use more ________ and form more ________

Reactants, products

30

Anything that doesn't affect the rate is _________ order

0

31

______________- decomposition reaction (order of reactant is 1)
______________- second order overall in reactants
______________- 3 or more reactants, overall order is 3

Unimolecular
Bimolecular
Termolecular

32

Catalyst, temperature, surface area, concentration all affect _________

Collisions

33

Your unit for k is M ^-___ s^-1

Overall order minus 1

34

Intermediates are ________ in early steps and ________ in later steps

Product, reactant

35

if concentration vs time is a straight line,
If concentration vs 1/time is a straight line,

Zero order Rxn
First order Rxn

36

An ______ gains heat while an ________ loses heat

Endothermic, exothermic