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Test1 ch15 Kinetics Practice Problems, Lecture notes of Chemical Kinetics

Evangelische Theologische Faculteit, LeuvenChemical Kinetics

Jasperse. Kinetics. Extra Practice Problems. General Types/Groups of problems: Rates of Change in Chemical Reactions p1 First Order Rate Law Calculations.

Typology: Lecture notes

2021/2022

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General Chemistry II Jasperse
Kinetics. Extra Practice Problems
General Types/Groups of problems:
Rates of Change in Chemical Reactions
p1
First Order Rate Law Calculations
P9
The look of concentration/time graphs
p2
Reaction Energy Diagrams, Activation
Energy, Transition States…
P10
Rates: Average Rates, Determination of Rates from
Stoichiometry and Changes of Other Chemicals
p3
Reaction Mechanisms,
Intermediates…
P12
Reactant Order and Overall Reaction Order
P4
Mechanism Steps and Rate Laws
P13
Given a Rate Law, How much will rate change with
change in concentration
P5
Catalysts
P14
Determining Reactant Orders from Actual Data
P6
Answers
P15
Actual Rate Law from Concentration/Rate Data
P7
Determining Rate Constant from Actual Data.
Where you yourself need to first deduce the rate law,
then plug in the values to solve for “k”.
P8
Rates of Change in Chemical Reactions
1. For the reaction A + 3B à 2C, how does the rate of disappearance of B compare to the rate of production
of C?
a. the rate of disappearance of B is 1/2 the rate of appearance of C
b. the rate of disappearance of B is 3/2 the rate of appearance of C
c. the rate of disappearance of B is 2/3 the rate of appearance of C
d. the rate of disappearance of B is 1/3 the rate of appearance of C
2. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔA would be written as:
a.
d.
+1/2 ΔA/Δt.
b.
e.
–2 ΔA/Δt.
c.
3. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔB would be written as
a.
d.
+1/3 ΔB/Δt
b.
e.
–3 ΔB/Δt
c.
4. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔC would be written as
a. +ΔC/Δt d. d. –4 ΔC/Δt
b. +4 ΔC/Δt e. –1/4 ΔC/Δt
c. +1/4 ΔC/Δt
5. In the combustion of methane, CH4(g) + 2 O2(g) → CO2(g) + 2 H2O (g), which reactant has the greatest rate
of disappearance?
a.
CH4
b.
O2
c.
CO2
d.
H2O
e.
CH4 and O2 have the same rate of disappearance.
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff

Partial preview of the text

Download Test1 ch15 Kinetics Practice Problems and more Lecture notes Chemical Kinetics in PDF only on Docsity!

General Chemistry II Jasperse

Kinetics. Extra Practice Problems

General Types/Groups of problems:

Rates of Change in Chemical Reactions p1 First Order Rate Law Calculations P

The look of concentration/time graphs p2 Reaction Energy Diagrams, Activation

Energy, Transition States…

P

Rates: Average Rates, Determination of Rates from

Stoichiometry and Changes of Other Chemicals

p3 Reaction Mechanisms,

Intermediates…

P

Reactant Order and Overall Reaction Order P4 Mechanism Steps and Rate Laws P

Given a Rate Law, How much will rate change with

change in concentration

P5 Catalysts P

Determining Reactant Orders from Actual Data P6 Answers P

Actual Rate Law from Concentration/Rate Data P

Determining Rate Constant from Actual Data.

Where you yourself need to first deduce the rate law,

then plug in the values to solve for “k”.

P

Rates of Change in Chemical Reactions

1. For the reaction A + 3B à 2 C, how does the rate of disappearance of B compare to the rate of production

of C?

a. the rate of disappearance of B is 1/2 the rate of appearance of C

b. the rate of disappearance of B is 3/2 the rate of appearance of C

c. the rate of disappearance of B is 2/3 the rate of appearance of C

d. the rate of disappearance of B is 1/3 the rate of appearance of C

2. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔA would be written as:

a. – ΔA/Δ t. d. +1/2 ΔA/Δ t.

b. – 1/2 ΔA/Δ t. e. – 2 ΔA/Δ t.

c. +ΔA/Δ t.

3. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔB would be written as

a. – ΔB/Δ t d. +1/3 ΔB/Δ t

b. +ΔB/Δ t e. – 3 ΔB/Δ t

c. – 1/3 ΔB/Δ t

4. For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔC would be written as

a. +ΔC/Δ t d. d. – 4 ΔC/Δ t

b. +4 ΔC/Δ t e. – 1/4 ΔC/Δ t

c. +1/4 ΔC/Δ t

5. In the combustion of methane, CH 4 ( g ) + 2 O 2 ( g ) → CO 2 ( g ) + 2 H 2 O ( g ), which reactant has the greatest rate

of disappearance?

a. CH 4

b. O 2

c. CO 2

d. H 2 O

e. CH 4 and O 2 have the same rate of disappearance.

The look of concentration/time graphs

  1. Which of the following is not a possible graph of concentration versus time for a reactant? a. c. b. d.
  2. Assuming that each of the following graphs has the same concentration and time axes, which has the greatest initial rate of disappearance of reactant? a. c. b. d.
  3. The following graph shows the kinetics curves for the reaction of oxygen with hydrogen to form water: O 2 ( g ) + 2H 2 ( g ) → 2H 2 O( g ). Which curve is hydrogen? a. the dashed curve b. the gray curve c. the black curve d. either the gray or the black curve

e. Any of these curves could be hydrogen

Reactant Order and Overall Reaction Order

15. For the reaction 2A + B + 2 C à D + 2E, the rate law is: rate =k[A]^2 [B]^1 [C]^1

Which of the following statements is false: a. the reaction is second order in [A] b. the reaction is first order in [B] c. the reaction is second order in [C] d. the reaction is 4th order overall

16. For the reaction 1A + 2B + 1C à 2D + 1E, the rate law is: rate =k [B]^2 [C]^1

Which of the following statements is false: a. the reaction is first order in [A] b. the reaction is second order in [B] c. the reaction is first order in [C] d. the reaction is third order overall

  1. For the rate law Rate = k [A]1/2[B], the partial order with respect to A is __________, the partial order with respect to B is __________, and the total order is __________. a. 1/2; 0; 1/ b. 1/2; 1; 1 c. 1/2; 1; 3/ d. 1/ e. The orders cannot be determined without a chemical reaction.
  2. For the rate law Rate = k [A][B]3/2, the order with respect to A is __________, the order with respect to B is __________, and the overall reaction order is __________. a. 0; 3/2; 3/ b. 1; 3/2 ; 1 c. 1; 3/2 ; 5/ d. 1; 3/2; 7/ e. The orders cannot be determined without a chemical reaction.
  3. The reaction A + 2B → C is first order in B and A. The overall order of the reaction is __________ a. first. d. zero. b. second. e. fourth. c. third.

Given a Rate Law, How much will rate change with change in concentration

  1. The reaction CHCl 3 ( g ) + Cl 2 ( g ) → CCl 4 ( g ) + HCl( g ) has the following rate law: Rate = k [CHCl 3 ][Cl 2 ]. If the concentration of CHCl 3 is increased by a factor of five while the concentration of Cl 2 is kept the same, the rate will a. double. d. increase by a factor of five. b. triple. e. decrease by a factor of one-fifth. c. stay the same.
  2. The reaction 2NO( g ) + O 2 ( g ) → 2NO 2 ( g ) has the following rate law: Rate = k [O 2 ][NO]^2. If the concentration of NO is reduced by a factor of two, the rate will __________ a. double. d. be reduced by one-half. b. quadruple. e. remain the same. c. be reduced by one-quarter.
  3. The rate of a reaction is found to double when the concentration of one reactant is quadrupled. The order of the reaction with respect to this reactant is __________ a. first. d. one-half. b. second. e. third. c. one-quarter.

Actual Rate Law from a Table of Concentration/Rate Data

  1. Given the following data, determine the rate law for the reaction NH 4 +( aq ) + NO 2 – ( aq ) → N 2 ( g ) + 2H 2 O() Experiment [NH 4 +] ( M ) [NO 2 – ] ( M ) Rate ( M /s) 1 0.2500 0.2500 (^) 1.25 × 10 –^3 2 0.5000 0.2500 (^) 2.50 × 10 –^3 3 0.2500 0.1250 (^) 6.25 × 10 –^4 a. k [NH 4 +][NO 2 – ] d. k [NH 4 +]1/2[NO 2 – ]^2 b. k [NH 4 +]^2 [NO 2 – ] e. k [NH 4 +][NO 2 – ]^2 c. k [NH 4 +][NO 2 – ]1/
  2. Given the following data, determine the rate law for the reaction 2NO( g ) + Cl 2 ( g ) → 2NOCl( g ) Experiment [NO] ( M ) [Cl 2 ] ( M ) Rate ( M /s) 1 0.0300 0.0100 3.4 × 10 –^4 2 0.0150 0.0100 8.5 × 10 –^5 3 0.0150 0.0400 (^) 3.4 × 10 –^4 a. Rate = k [NO][Cl 2 ] d. Rate = k [NO]^2 [Cl 2 ]^2 b. Rate = k [NO][Cl 2 ]^2 e. Rate = k [NO][Cl 2 ]1/ c. Rate = k [NO]^2 [Cl 2 ]
  3. What is the rate law for the reaction 2A + 2B + 2C à products Initial [A] Initial [B] Initial [C] rate 0.273 0.763 0.400 3. 0.819 0.763 0.400 9. 0.273 1.526 0.400 12. 0.273 0.763 0.800 6. a. rate = k[A][B][C] b. rate = k[A][B]^2 [C] c. rate = k[A]^3 [B]^4 [C]^2 d. rate = k[A]^2 [B]^2 [C]^2

Determining Rate Constant from Rate Law and Actual Data. Where you yourself need to first

deduce the rate law, then plug in the values to solve for “k”.

  1. The initial rate data for the reaction 2N 2 O 5 ( g ) → 4NO 2 ( g ) + O 2 ( g ) is shown in the following table. Determine the value of the rate constant for this reaction. Experiment N 2 O 5 Rate ( M /s) (^1) 1.28 × 102 22. 2 2.56 x 10^2 45. a. 4.09 s–^1 d. 0.225 s–^1 b. 0.176 s–^1 e. 80.1 s–^1 c. 0.0569 s–^1
  2. Given the following data, determine the rate constant of the reaction 2NO( g ) + Cl 2 ( g ) → 2NOCl( g ) Experiment [NO] ( M ) [Cl 2 ] ( M ) Rate ( M /s) 1 0.0300 0.0100 3.4 × 10 –^4 2 0.0150 0.0100 8.5 × 10 –^5 3 0.0150 0.0400 (^) 3.4 × 10 –^4 a. 1.13 M –^2 s–^1 d. 0.0265 M –^2 s–^1 b. 9.44 M –^2 s–^1 e. 59.6 M –^2 s–^1 c. 37.8 M –^2 s–^1

Reaction Energy Diagrams, Activation Energy, Transition States…

  1. Which point as labeled by an asterisk (*) on the following energy profile is the transition state? a. c. b. d.
  2. The energy profiles for four different reactions are shown. Which reaction requires the most energetic collisions to reach the transition state? a. a c. c b. b d. d
  1. The following energy profiles for four different reactions are shown. Which reaction is the most endothermic? a. a c. c b. b d. d
  2. The following energy profiles for four different reactions are shown. Which reaction is the most exothermic? a. a c. c b. b d. d
  3. Collision theory assumes that the rate of a reaction depends on __________ a. the energy of collisions. b. the orientation of colliding molecules. c. the energy of collisions and the orientation of colliding molecules. d. the change in energy between the products and the reactants. e. the change in free energy between the reactants and products.

Mechanism Steps, Slow Steps, and Rate Laws

  1. A proposed mechanism for the decomposition of ozone in the stratosphere is: Step 1: Cl( g ) + O 3 ( g ) → ClO( g ) + O 2 ( g ) Step 2: ClO( g ) + O 3 ( g ) → Cl( g ) + 2O 2 ( g ) What is the molecularity of Step 1? a. zeromolecular b. unimolecular c. bimolecular d. termolecular e. More information is needed to answer this question.
  2. A proposed mechanism for the reduction of nitrogen as NO by hydrogen is: Step 1: H 2 ( g ) + 2 NO( g ) → N 2 O( g ) + H 2 O( g ) Step 2: N 2 O( g ) + H 2 ( g ) → N 2 ( g ) + H 2 O( g ) What is the molecularity of Step 1? a. unimolecular b. bimolecular c. termolecular d. zero molecular (spontaneous) e. More information is needed to answer this question.
  3. The mechanism for the reaction 2H 2 O 2 ( aq ) → 2H 2 O() + O 2 ( g ) in the presence of I–( aq ) is proposed to be: Step 1: H 2 O 2 ( aq ) + I–( aq ) → H 2 O() + OI–( aq ) (slow) Step 2: H 2 O 2 ( aq ) + OI–( aq ) → H 2 O() + O 2 ( g ) + I–( aq ) (fast) What is the molecularity of the rate-determining step? a. zeromolecular b. unimolecular c. bimolecular d. termolecular e. More information is needed to answer this question.
  4. A proposed mechanism for the reduction of nitrogen as NO by hydrogen is: Step 1: H 2 ( g ) + 2NO( g ) → N 2 O( g ) + H 2 O( g ) (slow) Step 2: N 2 O( g ) + H 2 ( g ) → N 2 ( g ) + H 2 O( g ) (fast) What is the rate law? a. Rate = k [H 2 ][NO] b. Rate = k [H 2 ]^2 [NO] c. Rate = k [H 2 ][NO]^2 d. Rate = k [H 2 ]^2 [NO]^2 e. More information is needed to answer this question.
  5. The mechanism for the reaction 2H 2 O 2 ( aq ) → 2H 2 O() + O 2 ( g ) in the presence of I–( aq ) is proposed to be Step 1: H 2 O 2 ( aq ) + I–( aq ) → H 2 O() + OI–( aq ) (slow) Step 2: H 2 O 2 ( aq ) + OI–( aq ) → H 2 O() + O 2 ( g ) + I–( aq ) (fast) What is the rate law for the overall reaction? a. Rate = k [H 2 O 2 ] d. Rate = k [H 2 O 2 ][OI–] b. Rate = k [H 2 O 2 ]^2 e. Rate = k [H 2 O 2 ]^2 [I–]/[H 2 O] c. Rate = k [H 2 O 2 ][I–]

Catalysts

56. Which of the following statements about catalysts is false:

a. catalysts do not appear in the balanced equation

b. catalysts reduce the activation energy for a reaction

c. biological catalysts are called enzymes

d. catalysts do not alter the mechanism of the reaction and never appear in the rate law

e. since catalysts are recycled, even a small amount of catalyst can accelerate a reaction

57. Which of the following statements is false:

a. Changing the temperature does not change the activation energy for a reaction

b. At higher temperature a higher percentage of reactants have enough energy to get over the transition

state

c. The mechanism, rate law, and activation energy will all change when a catalyst is added.

d. The general rate law for a reaction does not changes with temperature, but the rate constant does change

e. The rate constant “k” for a reaction does not change when the temperature increases.

  1. A proposed mechanism for the following reaction is shown below. Identify the catalyst in the reaction. 2H 2 O 2 ( aq ) → 2H 2 O(aq) + O 2 in the presence of I–( aq ) Step 1: H 2 O 2 ( aq ) + I–( aq ) → H 2 O() + OI–( aq ) (slow) Step 2: H 2 O 2 ( aq ) + OI–( aq ) → H 2 O() + O 2 ( g ) + I–( aq ) (fast) a. H 2 O 2 d. H 2 O b. OI–^ e. O 2 c. I–
  2. The steps in a reaction mechanism are as follows. Which species is acting as a catalyst? Step 1: Ag+( aq ) + Ce4+( aq ) ↔ Ag2+( aq ) + Ce3+( aq ) Step 2: Tl+( aq ) + Ag2+( aq ) → Tl2+( aq ) + Ag+( aq ) Step 3: Tl2+( aq ) + Ce4+( aq ) → Tl3+( aq ) + Ce3+( aq ) a. Ag+^ d. Ag2+ b. Tl+^ e. Tl3+ c. Ce3+