Chem 2 Exam 1 Practice Questions (Kinetics)

2.9) What is the concentration of a reactant after 22.0 s if the initial concentration is 0.150 M and the rate constant is 5.4 x 10^-2 s^-1?

0.0457 M

10) What is the rate at which Br- (aq) disappears in the reaction below if the rate of disappearance of BrO3-(aq) is 0.048 M/s? BrO3{-} + 5Br{-} + 6H{+} --> 3Br2 + 3H2O

0.24 M/s

2.14) What is the concentration of A after 10.5 minuets for the zero-order reaction A -->products when the initial concentration of A is 0.400M? (k=0.00762 M/min)

0.320 M

24) Consider the table of data collected for the reaction A-->Products. Determine the magnitude (value) of the reaction rate constant by graphing the data appropriately. First Order --------------------------- Time (s) [A] 0.00 0.600 1.50 0.325 3.00 0.178 4.50 0.095 6.00 0.050 7.50 0.028 9.00 0.015 ----------------------------

0.41

2.13) What is the concentration of A after 10.5 minutes for the reaction A--> Products when the initial concentration of A is 0.750M? (k=0.0457 M^-1 min^-1)

0.552 M

2) For the reaction A(g) --> B(g) + 4 C(g) What is the rate of pressure change for C if the pressure change for A is -0.195 atm/s?

0.780 atm/s

2.15) The half-life of element x is 500 years. If there are initially 8g of x, how much will remain after 1500 years?

1.0 g

2.7) how long will it take for the concentration of A to decrease from 0.500M to 0.200M in the first order reaction A--> B? (k=0.800 s^-1)

1.15 s

3) For the reaction A + 2B --> 3C + D What is the magnitude of the rate of change for [D] when [C] is increasing at 4.6 M/s?

1.5 M/s

Second order graphs are..... Whats on the X and Y axis

1/[A] is on the y axis Time is on the x axis They are Positive and linear

2.8) What amount of time is required for the concentration of A to decrease from 0.800 to 0.200M in the zero order reaction A-->B? (k=0.0567 M s^-1)

10.6 s

2.22) The gas phase decomposition of NO2(g) 2NO2(g) --> 2NO(g) + O2(g) Obeys the second order rate law Rate=k[NO2]^2, with a rate constant k=0.543 M^-1s^-1 at 300 degrees C. Starting with [NO2]=0.210M, how long will it take for the [NO2] to decrease to 5.00% of its starting value?

167 s

2.4) If a reaction is first order with a rate constant of 0.0450 s^-1, how much time is required for 65% of the initial quantity of the reactant to be consumed?

23 s

2.16) If the first-order half-life of tritium(3H) is 12.26 years, what amount of time is necessary for it to lose 75% of its radioactivity?

24.5 years

20) The reaction A + 2B + C --> Products has a rate law of Rate = k[A]^2[B]. By what factor would the reaction change is [B] is tripled?

3

2.12) How long will it take for the concentration of A to decrease from 1.400M to 0.205M for the zero order reaction A--> Products? (k=0.0345M/s)

34.6 s

25) What is the overall reaction order for the following rate law? Rate= k[A][B][C]^2

4

2.6) A reaction was shown to follow second-order kinetics. How much time is required for [A] to change from 0.500M to 0.250M? (k=0.456 M^-1s^-1)

4.39 s

2.11) How long will it take for the concentration of A to decrease from 0.910M to 0.205 for the reaction A--> Products? (k=0.152 M/s)

4.61 s

2.19) A first-order reaction initially contains 1.00 x 10^20 molecules. If the reaction has a half-life of 20.0 minutes, how many molecules remain unreacted after 80.0 minuets?

6.23 x 10^18 molecules

21) The reaction A + B --> 2C has the rate law Rate = k[A][B]^3. By what factor does the rate of reaction increase when [A] remains constant by [B] is doubled?

8

29) For the reaction 3A + 4B --> 2C + D, what is the magnitude of the rate of change for [B] when [D] is increasing at 2.4 M/min?

9.6 M/min

2.5) What is the order of the reaction A--> B + C when a graph of ln[A] vs time gives a straight line with a negative slope?

First

Delete this card - We won't be graphing on the Exam 26) Consider the table of data collected for the reaction A--> Products. Determine the order of the reaction by graphing the data appropriately. ---------------------------- Time (s) [A] 0.00 0.600 1.50 0.325 3.00 0.178 4.50 0.095 6.00 0.050 7.50 0.028 9.00 0.015 ----------------------------

First Order

No graphing on the Exam 28) Determine the order of the reaction by graphing the data appropriately. --------------------------- Time (s) [A] 0.00 0.600 0.50 0.325 1.00 0.178 1.50 0.098 2.00 0.050 2.50 0.028 3.00 0.015 3.50 0.008 4.00 0.004 -------------------------

First Order

What are the units of k for a Zero order reaction?

M s^-1

1) What are the units for the rate constant of a reaction with the rate law Rate = k[A][B] ?

M^-1 s^-1

What are the units of k for a Second order reaction?

M^-1 s^-1

What are the units of k for a Third order reaction?

M^-2 s^-1

34) Determine the magnitude of the reactions rate by graphing ------------------------------ Time (s) [A] 0.00 0.500 1.50 0.420 3.00 0.335 4.50 0.250 6.00 0.170 7.50 0.085 9.00 0.003 -------------------------------

Magnitude = 0.0552

11) Consider the table of data collected for the reaction A --> Products. Determine the magnitude (value) of the reaction rate constant by graphing the data appropriately. ------------------------------- Time (s) [A] 0.00 0.750 0.50 0.665 1.00 0.575 1.50 0.490 2.00 0.410 2.50 0.320 3.00 0.235 3.50 0.150 4.00 0.060 ------------------------------

Magnitude = 0.173

14) Consider the table of data collected for the reaction A --> Products. Determine the magnitude (value) of the reaction rate constant by graphing the data appropriately. ----------------------- Time (s) [A] 0.00 0.450 0.50 0.300 1.00 0.255 1.50 0.180 2.00 0.150 2.50 0.130 3.00 0.115 3.50 0.100 4.00 0.090 -----------------------

Magnitude = 2.2

19) A reaction has a rate law of Rate = (1.25 M^-1s^-1)[A][B] What is the rate of the reaction if...? [A] = 0.417 M [B] = 0.280 M

Rate = 0.146 M/s

6) Determine the rate law or the reaction given the following experiment data. A + B --> C + D ---------------------------------------------- Trial [A] [B] Initial Rate (M/min) 1 0.25 0.40 7.25 2 0.75 0.40 21.5 3 0.50 0.80 14.5 4 0.75 0.80 21.5 ----------------------------------------------

Rate = k[A]

4) Using the information in the table, the rate law for the reaction is... 2A(g) + B(g) --> C(g) + D(g) -------------------------------------- [A] [B] Rate (M/min) 0.150 0.300 3.38 x 10^-5 0.450 0.300 1.01 x 10^-4 0.450 0.150 2.54 x 10^-5 --------------------------------------

Rate = k[A][B]^2

18) Using the information in the table, the rate law for the reaction is.... A(g) + 3B(g) --> C(g) + 2D(g) ------------------------------- [A] [B] Rate (M/s) 0.300 .180 0.0234 0.300 0.360 0.0934 0.150 0.180 0.0234 -------------------------------

Rate = k[B]^2

15) The following reaction was found to be first order in each of the two reactants and second order overall. The rate law is therefore... 2NO(g) + O2(g) ---> 2NO2(g)

Rate = k[NO][O2]

2.2) If the plot of 1/[A] verses time produces a straight line with a positive slope for the reaction A --> B + C, what is the order of the reaction?

Second

No graphing on Exam Determine the order of the reaction by graphing. ------------------------------- Time (s) [A] 0.00 0.450 0.50 0.300 1.00 0.255 1.50 0.180 2.00 0.150 2.50 0.130 3.00 0.115 3.50 0.100 4.00 0.090 ---------------------------------

Second Order

No graphing on test 35) Determine the order of the reaction by graphing. ------------------------------- Time (s) [A] 0.00 0.500 1.50 0.420 3.00 0.335 4.50 0.250 6.00 0.170 7.50 0.085 9.00 0.003 ------------------------------

Zero Order

23) Consider the table of data collected for the reaction A-->Products. Determine the order of the reaction by graphing the data appropriately. -------------------------- Time (s) [A] 0.00 0.750 0.50 0.665 1.00 0.575 1.50 0.490 2.00 0.410 2.50 0.320 3.00 0.235 3.50 0.150 4.00 0.060 --------------------------

Zero order

Zero order graphs are..... Whats on the X and Y axis

[A] is on the y axis Time is on the x axis They are Negative and linear

5) Which of the following changes could double the rate of the reaction with a rate law of Rate = k[A][B]^2 ? 2A(g) + B(g) + 3C(g) --> 3D(g) + E(g) a) Double [A] b) Double [B} c) Double [C] d) Cut [A] in half

a) Double [A]

16) Copper roofs on houses form panita (copper carbohydrates) over the course of years due to the reaction with oxygen, carbon dioxide, and water in the air. Which of the following statements is incorrect for this process? a) The Reaction has a low activation energy b) The reaction has a low reaction rate c) The formation of panita would occur faster during the summer than in the winter d) The formation of panita would occur slower at higher altitudes due to lower concentration of reactant e) Adding a catalyst would increase the rate of the panita forming

a) The Reaction has a low activation energy

7) What are the units for the rate constant of a first order reaction? a) s^-1 b) Ms^-1 c) M^-1s^-1 d) M^-2s^-1 e) sM^-1

a) s^-1

2.20) The breakdown of glucose to carbon dioxide and water does not occur at a discernible rate at body temperature, yet this reaction happens constantly in the human body. What type of molecule makes this possible? a) DNA b) Enzymes c) Blood d) Salts e) Lipids

b) Enzymes

30) What species has the greatest rate of disappearance in the reaction below? CH4 + 2O2 --> CO2 + 2H2O a) CH4 b) O2 c) CO2 d) H2O e) CH4 and O2 have identical rates

b) O2

33) Which of the following will decrease the rate of a reaction? a) Adding a catalyst to the reaction b) Increasing the temperature c) Decreasing the surface area of a solid reactant d) Increasing the concentration of the reactants

c) Decreasing the surface area of a solid reactant

2.3 Which equation is used to determine the amount of time required for the initial concentration to decrease by 45% if the rate constant has units of s-1? a) t = ln(2)/k b) Rate =k[A] c) ln([A]/[A]0) = -kt d) [A] = [A]0 -kt e) 1/[A] = 1/[A]0 + kt

c) Ln([A]/[A]0) = -kt

13) All of the following are factors that affect the rate of a reaction except... a) The concentration of the reactants b) Presence of a catalyst c) The magnitude of the equilibrium constant d) The temperature of the reaction e) The surface area of the solid reactants

c) The magnitude of the equilibrium constant

32) Which of the following is true for a reaction at equilibrium? a) The rate of the forward reaction is greater than the rate of the reverse reaction b) The rate of the forward reaction is less than the rate of the reverse reaction c) The rate of the forward reaction is equal to the rate of the reverse reaction d) the rates of the forward and reverse reactions become zero because the reaction stops e) The rates of the forward and reverse reactions can no longer be determined

c) The rate of the forward reaction is equal to the rate of the reverse reaction

2.21) Catalysts increase reaction rates by ___________ a) Increasing the activation energy b) Increasing the enthalpy of reaction c) Decreasing the enthalpy of reaction d) Providing an alternate reaction mechanism with a lower activation energy e) Changing the value of the equilibrium constant

d) Providing an alternate reaction mechanism with a lower activation energy

9) The reaction rate of a reaction at 60 degrees C will be greater than at 30 degrees C because . . . a) The higher temperature leads to greater surface area on solid or liquid reactants b) The reactants at 60 degrees C will be moving with too great of speed to collide effectively c) The activation energy will be lower at 60 degrees C d) There is a greater proportion of reactants with the necessary Kinetic energy to react e) There is a greater likelihood that the reactants will have the correct orientation to collide effectively

d) There is a greater proportion of reactants with the necessary Kinetic energy to react

22) Which of the following is equivalent to the rate at which ClO2-(aq) is appearing in the reaction? 2ClO2(aq) + 2OH-(aq) --> ClO2-(aq) +ClO3-(aq) +H2O(l) a) +1/2Δ[ClO2]/Δt b) -Δ[H2O]/Δt c) +Δ[OH-]/Δt d) +1/2Δ[OH-]/Δt e) +Δ[ClO3-]/Δt

e) +Δ[ClO3-]/Δt

31) Which of the following statements is correct concerning the reaction 2A + B --> 2C + 2D a) The reaction is second-order overall b) The reaction is third-order overall c) The rate is equal to k[A]^2[B] d) The rate is equal to k[A][B] e) It is not possible to determine the overall order nor the rate law from the given information

e) It is not possible to determine the overall order nor the rate law from the given information

17) Using the information in the table, the value of the rate constant for the reaction is.... 2A(g) + B(g) --> C(g) + D(g) ----------------------------------- [A] [B] Rate (M/min) 0.150 0.300 3.38 x 10^-5 0.450 0.300 1.01 x 10^-4 0.450 0.150 2.54 x 10^-5 -------------------------------------

k = 0.00250 M^-2 min^-1

2.10) What is the rate constant of a first-order reaction when 20.0% of a reactant remains after 30.0 s?

k = 0.054 s^-1

2.18) What is the rate constant of a first-order reaction if the half-life is 2.50 min?

k = 0.277 min^-1

2.17) The radioisotope 14C (half-life = 5730 years) is used for carbon dating. What is the first-order rate constant?

k = 1.21 x 10^-4 years^-1

12) Using the information in the table, the value of the rate constant for the reaction is... 2A(g) + B(g) --> C(g) +D(g) ----------------------------- [A] [B] Rate (M/s) 0.100 2.50 0.460 0.200 2.50 0.920 0.300 1.25 1.38 -----------------------------

k = 4.6 s^-1

First order graphs are..... Whats on the X and Y axis

ln[A] is on the y axis Time is on the x axis They are Negative and linear

What are the units of k for a first order reaction?

s^-1