HChem Chemical Kinetics Test Flashcards
The enthalpy change is the _____ of the reaction and is found by ____________
Heat
Products-reactants
The activation energy=
Activated complex-reactants
Enthalpy changed and activation energy have what unit?
In
The strongest bonds are where the _____ energy is greatest
Kinetic (potential energy is weakest)
The weakest bonds are where the ____ energy is strongest
Potential (kinetic is weakest)
Why are bonds with greater potential energy weaker
They are closer to the activated complex and it takes less force to break the bonds
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
What is the activated complex
The intermediate created at the peak of the reaction
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
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
A slow reaction would start with a ______ PE
High
The activated complex of a step is represented by the ____ while the intermediate is represented by the __________
Peak, valley at the bottom
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
Adding a catalyst to any step but the RDS will/will not affect the reaction rate
Will not
If a catalyst is discovered that increases the rate of the RDS, how will the overall reaction be affected
It will increase
The RDS has the _____ peak
Highest
The sum of your elementary step will equal the ______ reaction
Overall
How do you know which of two fast steps will be faster
Check for intermediates
A catalyzed reaction will ____ at the same place but have a smaller ___________
Begin, activation energy (shorter peak)
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
Be sure to check the ______ in scientific notation to make sure it is negative/positive
Exponent
Check the unit in the box for __________ to know what it should be in the answer
Reaction rate (usually M/s)
If volume decreases, equilibrium will shift towards the side with _____ moles
Less
Intermediates may not appear in _________, but sometimes they have a substitute in the mechanism
Reaction rates
Catalysts are __________ in an early step in the mechanism an a ________ in a later step
Reactant, product
Increasing the volume of system will shift the equilibrium towards the side with _____ moles of gas
More
Decreasing the volume of a system will shift the equilibrium to the side with _______ moles of gas
Less
When is a reaction at equilibrium
Rate of formation on one side=one of formation on the other
If forward direction was favored, you use more ________ and form more ________
Reactants, products
Anything that doesn’t affect the rate is _________ order
0
______________- decomposition reaction (order of reactant is 1)
______________- second order overall in reactants
______________- 3 or more reactants, overall order is 3
Unimolecular
Bimolecular
Termolecular
Catalyst, temperature, surface area, concentration all affect _________
Collisions
Your unit for k is M ^-___ s^-1
Overall order minus 1
Intermediates are ________ in early steps and ________ in later steps
Product, reactant
if concentration vs time is a straight line,
If concentration vs 1/time is a straight line,
Zero order Rxn
First order Rxn
An ______ gains heat while an ________ loses heat
Endothermic, exothermic
