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1) 
Explain how collisions of reactant molecules determine the rate of a reaction.


A) 
What factors can increase the number of effective collisions in a reaction?


B) 
What other factors influence reaction rate?


2) 
Explain activation energy.


A) 
How does activation energy affect the rate of a reaction?


B) 
If activation energy is high, will the reaction be fast or slow?


3) 
Look at a potential energy diagram that shows the effect of a catalyst.


A) 
Explain how to find activation energy (E_{a})


B) 
Explain the purpose of a catalyst and how it changes E_{a}, ∆H and rate of a reaction.


4) 
How does doubling the concentration of a first order reaction affect the rate?


A) 
A second order reaction?


B) 
A zero order reaction?


5) 
What do you graph on the x axis and y axis to check the order of a reaction (linear test plot)?


6) 
Write the integrated rate law and the half life equation for the following types of reactions:


7) 
A certain firstorder reaction is 50% complete in 3.5 hours. What period of time is required for the reaction to be 88% complete?
Since the reaction is 50% complete in 3.5 hours, that is the half life. For the reaction to be 88% complete, there has to be 12% of the orginal amount left. I set the [A]_{o} as 1 and the [A]_{t} as 0.12 to reflect this.


8) 
A reaction mechanism is proposed to consist of three steps:


A) 
Write the balanced equation for the overall reaction.
+
→


B) 
Does this reaction use a catalyst?
If so, identify the catalyst(s):


C) 
Does this reaction contain an intermediate?
If so, identify the intermediate(s):
&


D) 
Which step is the rate determining step?


E) 
Write the rate law.
Rate =


9) 
Given: 2 NOBr → 2 NO + Br_{2} rate = k[NOBr]^{2} k = 0.80 M^{1} s^{1}


A) 
Determine half life when [NOBr]_{o} = 0.650 M.
seconds


B) 
Calculate [NOBr] at t = 5.80 X 10^{3} s if [NOBr]_{o} = 0.650 M.
M


C) 
If [NOBr]_{o} = 1.00 M, how long would it take for 80% NOBr to react?
seconds


10) 
The reaction 2 N_{2}O_{5} → 4 NO_{2} + 5 O_{2} obeys the rate law: rate = ^{Δ[N2O5]} / _{Δt} = k[N_{2}O_{5}]


A) 
If the initial concentration of N_{2}O_{5} is 4.0 x 10^{2} M at the same temperature as above, what is the initial rate of the reaction? (k = 3.4 x 10^{4} sec^{1})
M/sec


B) 
What is the halflife for this reaction?
seconds


C) 
What is the concentration after 10 minutes?
M


D) 
How much time will have passed when the concentration of N_{2}O_{5} reaches 0.015 M?
seconds


11) 
Observe the data in the chart for the following reaction and answer the questions.
A + B + C → D


A) 
Determine the order for each reactant.
[A]
[B]
[C]


B) 
Write the rate law for this reaction.
Rate = _{k [A]}
_{[B]}
_{[C]}


C) 
Find the value and units for "k."


D) 
What is the rate when [A] = 0.60 M, [B] = 0.40 M & [C] = 0.20 M?
M/sec


12) 
The decomposition of N_{2}O obeys zero order kinetics.
Given a rate constant = 2.46 X 10^{3} M/s and [N_{2}O] at 120 seconds is 0.155 M, calculate [N_{2}O]_{o}
M


13) 
Determine rate law from the following mechanism:


A) 
A + B → C (slow)
C + E → F (fast)
Rate =


B) 
A + B → C (fast)
C + E → F (slow)
Rate =


14) 
Consider the hypothetical reaction: A + B → P. For each of the possible rate laws listed below, indicate the reaction order with respect to A, with respect to B, and the overall reaction order.


A) 
Rate = k[A][B]
[A] =
[B] =
Overall =


B) 
Rate = k[A]^{2}
[A] =
[B] =
Overall =


C) 
Rate = k[A][B]^{2}
[A] =
[B] =
Overall =


15) 
What units would each of the rate constants in question #14 have if concentration is expressed as M and rate as M/sec?


A) 
Rate = k[A][B]
Units for k =


B) 
Rate = k[A]^{2}
Units for k =


C) 
Rate = k[A][B]^{2}
Units for k =


16) 
Given the data and the graphs below determine the order of this reaction.


What is the order of the reaction?
How do you know?

What is the value for k in this reaction?
k =

What is [C_{2}H_{6}] after 5000 seconds?
[A]_{t} =
M

17) 
Consider the following reaction: A + 2 B → C for which the following data is given:


A) 
Write the rate law expression for this reaction.
Rate =


B) 
What is the order with respect to A?
With respect to B?
What is the overall reaction order?


C) 
What is the numerical value for the rate constant with units?


D) 
What is the rate of appearance of C when [A] = 0.1 and [B] = 0.3?
M/sec


Multiple Choice:

18) 
For the following reaction: A → B + C that is second order, a linear plot will result when time is plotted against:


19) 
Which of the following statements is TRUE for the catalyzed and uncatalyzed versions of the same reaction?


20) 
Catalysts lower the activation energy of a reaction by:


21) 
For a first order reaction with a rate constant k = 3.13 x 10^{2} s^{1}, how long does it take for the concentration of the only reactant to become 40% of the original amount?


22) 
Increasing the temperature at which a reaction occurs speeds up the reaction by:


23) 
The decomposition of a substance is found to be first order. If it takes 2.5 x 10^{3} sec for the concentration of that substance to fall to half of its original value, find the rate constant.
sec^{1}


24) 
A reaction that is second order in A is 50.0% complete after 350 min. If [A] = 1.35 M, what is the rate constant?
M^{1}min^{1}


25) 
The decomposition of NOBr is second order: 2 NOBr → 2 NO + Br_{2} The rate constant for the reaction at 10°C is 0.80 M^{1}sec^{1}. If [NOBr]_{o} = 0.052 M, what is [NOBr] after the reaction has run for 1.0 min?
M


26) 
Given: SO_{2}Cl_{2} → SO_{2} + Cl_{2} First order with a rate constant of 2.2 x 10^{5} sec^{1} at 320°C. What percentage of a sample of SO_{2}Cl_{2} will remain if it is heated for 5.00 hr at 320°C?
%
Because it is looking for the percentage remaining, I set [A]_{o} equal to 100, so that when I find [A]_{t}, it will automatically be a percentage of [A]_{o}.


27) 
The rate constant for the first order reaction of the conversion of cyclopropane to propene at 500°C is 5.5 x 10^{4} sec^{1}.


a) 
Find the halflife of cyclopropane at 500°C.
M


b) 
Given an initial cyclopropane concentration of 1.0 x 10^{3} M at 500°C, find the concentration of cyclopropane that remains after 2.0 hr.
sec


28) 
Calculate the time required for the concentration to decrease to 1/10 of its initial value for a first order reaction with a k = 10.0 sec^{1}.
sec

