Question 1

Why does the rate of a reaction generally slow with time?

Accepted Answer

A)  The reaction mixture gets warmer. 
B)  The number of product molecules decreases. 
C)  The number of collisions of reactants decreases. 
D)  The number of product molecules increases. 
E)  The temperature of the reaction vessel decreases. 
A)  The reaction mixture gets warmer. 
B)  The number of product molecules decreases. 
C)  The number of collisions of reactants decreases. 
D)  The number of product molecules increases. 
E)  The temperature of the reaction vessel decreases.

Question 2

For a large number of reactions in organic chemistry, an increase in temperature 10°C over room temperature will double the rate. What activation energy does this correspond to?

Accepted Answer

The answer of For a large number of reactions in...

Question 3

The reaction of NO2 with CO to give CO2 and NO can proceed through different mechanisms. What first step would be consistent with the following rate law?Rate = k[NO2][CO]

Accepted Answer

NO<sub>2</

Question 4

Which of the following are bimolecular processes?
I.  
II. NO  $\rarr$  ONNO
III. H2C = CHCH3 + H2SO4  $\rarr$ CH3CH(OSO2(OH))CH3
IV.  
V. H2  $\rarr$  2 H•

Accepted Answer

A)  I and V 
B)  I, IV and V 
C)  II only 
D)  II and III 
E)  II, III and V 
A)  I and V 
B)  I, IV and V 
C)  II only 
D)  II and III 
E)  II, III and V

Question 5

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H3O+(aq) + Cr2O72- + 6Fe2+(aq)  $\rarr$  2Cr3+(aq) + 21H2OWhat is the rate of increase of Cr3+ concentration expressed in terms of changing H3O+ concentration?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 6

The reaction of NO with O2 to give oxygen is known to follow a third order rate law(rate = k[NO]2[O2]). Two possible mechanisms are shown below:   Which of these two mechanisms is a more acceptable mechanism, based on the criteria given above?

Accepted Answer

A)  Mechanism 1 because it is simpler 
B)  Mechanism 1 because its rate law is the same as the known rate law 
C)  Mechanism 2 because it only involves 2 steps 
D)  Mechanism 2 because only bimolecular processes are involved 
E)  Mechanism 1 because no unstable species are formed 
A)  Mechanism 1 because it is simpler 
B)  Mechanism 1 because its rate law is the same as the known rate law 
C)  Mechanism 2 because it only involves 2 steps 
D)  Mechanism 2 because only bimolecular processes are involved 
E)  Mechanism 1 because no unstable species are formed

Question 7

It is determined that the charcoal in a fire pit used as an ancient hearth has lost about 42.3% of the initial 14C. How old was the fire pit if 14C has a half life of 5730 years?

Accepted Answer

A)  2210 years 
B)  4430 years 
C)  4550 years 
D)  5250 years 
E)  7750 years 
A)  2210 years 
B)  4430 years 
C)  4550 years 
D)  5250 years 
E)  7750 years

Question 8

At moderate temperatures, the rate law for the reaction of NO2 and CO to give CO2 and NO follows the rate law shown below:rate = k [NO2]2   In which flask will the reaction be faster and how much faster?

Accepted Answer

flask b; f

Question 9

The rate law for the reaction of NO with O2 to give NO2 is shown below:rate = k [NO]2[O2]
a) If all other conditions are kept constant, what will be the effect on the rate if the concentration of NO is doubled?
b) If all other conditions are kept constant, what will be the effect on the rate if the concentration of O2 is doubled?

Accepted Answer

a) quadrup

Question 10

The reaction of NO2 with CO to give CO2 and NO can proceed through different mechanisms. What rate law would be consistent for the following first step?
2 NO2 $\rightarrow$ NO + NO3

Accepted Answer

Rate = k[N

Question 11

Cyclohexane is manufactured from the reaction of benzene with hydrogen:
C6H6(g) + 3 H2(g)  $\rarr$ C6H12(g)
If the initial concentration of hydrogen was 1.5 M and 5 minutes later the hydrogen concentration is 0.34 M, what is the average rate of appearance of cyclohexane?

Accepted Answer

A)  0.39 M/min 
B)  7.7 x 10-2 M/min 
C)  4.6 M/s 
D)  3.9 x 10- 2 M/hr 
E)  2.3 M/min 
A)  0.39 M/min 
B)  7.7 x 10-2 M/min 
C)  4.6 M/s 
D)  3.9 x 10- 2 M/hr 
E)  2.3 M/min

Question 12

Sucrose, cane sugar, reacts with water in acid solution to give glucose and fructose, which have the same chemical formula.
C12H22O11 (aq) + H2O (l) $\rightarrow$2 C6H12O6 (aq)
The following data were obtained at room temperature for sucrose:   Use graphical means to determine the order of the reaction and write the rate law with the numerical value of the rate constant with time units of seconds.

Accepted Answer

first order; rate =

Question 13

Which of the following does NOT occur during a reaction facilitated by a heterogeneous catalyst?

Accepted Answer

A)  rejuvenation of catalyst via desorption of products 
B)  migration of bound reactants over catalyst surface 
C)  bond reorganization at catalyst surface 
D)  absorption of reactants on catalyst surface 
E)  weakening of or breaking of bonds and formation of bonds/interactions with catalyst 
A)  rejuvenation of catalyst via desorption of products 
B)  migration of bound reactants over catalyst surface 
C)  bond reorganization at catalyst surface 
D)  absorption of reactants on catalyst surface 
E)  weakening of or breaking of bonds and formation of bonds/interactions with catalyst

Question 14

The reaction A + 2B  $\rarr$  products was found to have the rate law;
 rate = k[A] [B]2. While holding the concentration of A constant, the concentration of B was increased from 0.010M to 0.030M. Predict by what factor the rate of reaction will increase.

Accepted Answer

A)  3 
B)  6 
C)  9 
D)  30 
E)  27 
A)  3 
B)  6 
C)  9 
D)  30 
E)  27

Question 15

Nitrogen dioxide, NO2 will react with carbon monoxide, CO, to form nitric oxide, NO, and carbon dioxide, CO2. A proposed mechanism is:
2NO2 $\rarr$ NO3 + NO
NO3 + CO  $\rarr$ NO2 + CO2
Experiments indicate that the rate of the reaction is independent of the CO concentration. Identify the rate determining step and derive the rate law consistent with the mechanism and experimental observation.

Accepted Answer

Since rate is independent of C

Question 16

A 1.66 x 10-4 mole sample of 239Pu undergoes 9 x 107 decays per second obeying first-order kinetics. How many decays per second would be expected from a 5.46 x 10-1 mole sample?

Accepted Answer

A)  9 x 108 decays/second 
B)  3 x 109 decays/second 
C)  9 x 1010 decays/second 
D)  3 x 1011 decays/second 
E)  9 x 1011 decays/second 
A)  9 x 108 decays/second 
B)  3 x 109 decays/second 
C)  9 x 1010 decays/second 
D)  3 x 1011 decays/second 
E)  9 x 1011 decays/second

Question 17

Hydrogen and iodine react to form HI. One possible mechanism is shown below:I2(g)   2 I(g)
H2(g) + 2 I(g)  $\rarr$ 2 HI(g)
Consider the following statements in light of this mechanism:
I. The rate law overall is second order.
II. The iodine atom is an intermediate.
III. The first step is the rate determining step.
IV. The second step is the fast step.
V. The second step is rate determining.
Which of the above statements are true?

Accepted Answer

A)  II, III and IV 
B)  II and V 
C)  all except V 
D)  I and II only 
E)  I, II and V 
A)  II, III and IV 
B)  II and V 
C)  all except V 
D)  I and II only 
E)  I, II and V

Question 18

Show that the mechanism and rate law are closely related.

Accepted Answer

The mechanism must be the sum

Question 19

A particular first-order reaction is characterized by activation energy of 50 kJ/mole. At what temperature would the rate of the reaction be 10 times that at 298oK?

Accepted Answer

Need to recognize that for fir

Question 20

For the following reaction A + B $\rightarrow$ C + D, the rate law is determined to be Rate = k[A]2a) Of the five proposed mechanisms shown below, which is consistent with the experimentally determined rate law?
1. 2 A $\rightarrow$ Z (slow)2 B + Z $\rightarrow$ 2 C + 2 D (fast)
2. A + B $\rightarrow$ C + D (slow)
3. 2 B $\rightarrow$ N (slow)2 A + N $\rightarrow$ 2 C + 2 D (fast)
4. A $\rightarrow$ X (slow)B + X $\rightarrow$ C + D (fast)
5. B $\rightarrow$ M (slow)A + M $\rightarrow$ C + D (fast)b) 
Are there any intermediates in the mechanism you chose and if so what?

Accepted Answer

The answer of For the following reaction A + B...

Why does the rate of a reaction generally slow with time?

For a large number of reactions in organic chemistry, an increase in temperature 10°C over room temperature will double the rate. What activation energy does this correspond to?

The reaction of NO₂ with CO to give CO₂ and NO can proceed through different mechanisms. What first step would be consistent with the following rate law?Rate = k[NO₂][CO]

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H₃O⁺(aq) + Cr₂O₇^2-+ 6Fe²⁺(aq) $\rarr$ 2Cr³⁺(aq) + 21H₂OWhat is the rate of increase of Cr³⁺ concentration expressed in terms of changing H₃O⁺concentration?

The reaction of NO with O₂ to give oxygen is known to follow a third order rate law(rate = k[NO]²[O₂]). Two possible mechanisms are shown below: Which of these two mechanisms is a more acceptable mechanism, based on the criteria given above?

It is determined that the charcoal in a fire pit used as an ancient hearth has lost about 42.3% of the initial ¹⁴C. How old was the fire pit if ¹⁴C has a half life of 5730 years?

At moderate temperatures, the rate law for the reaction of NO₂ and CO to give CO₂ and NO follows the rate law shown below:rate = k [NO₂]² In which flask will the reaction be faster and how much faster?

The reaction of NO₂ with CO to give CO₂ and NO can proceed through different mechanisms. What rate law would be consistent for the following first step? 2 NO₂ $\rightarrow$ NO + NO₃

Cyclohexane is manufactured from the reaction of benzene with hydrogen: C₆H₆(g) + 3 H₂(g) $\rarr$ C₆H₁₂(g) If the initial concentration of hydrogen was 1.5 M and 5 minutes later the hydrogen concentration is 0.34 M, what is the average rate of appearance of cyclohexane?

Which of the following does NOT occur during a reaction facilitated by a heterogeneous catalyst?

The reaction A + 2B $\rarr$ products was found to have the rate law; rate = k[A] [B]². While holding the concentration of A constant, the concentration of B was increased from 0.010M to 0.030M. Predict by what factor the rate of reaction will increase.

A 1.66 x 10^-4 mole sample of ²³⁹Pu undergoes 9 x 10⁷ decays per second obeying first-order kinetics. How many decays per second would be expected from a 5.46 x 10^-1 mole sample?

Show that the mechanism and rate law are closely related.

A particular first-order reaction is characterized by activation energy of 50 kJ/mole. At what temperature would the rate of the reaction be 10 times that at 298^oK?

Fundamental Concepts of Chemistry

The Behaviour of Gases

Energy and Its Conservation

Atoms and Light

Atomic Energies and Periodicity

Fundamentals of Chemical Bonding

Theories of Chemical Bonding

Effects of Intermolecular Forces

Properties of Solutions

Organic Chemistrystructure

Organic Chemistryreactions

Spontaneity of Chemical Processes

Principles of Chemical Equilibrium

Aqueous Acidbase Equilibria

Applications of Aqueous Equilibria

Electron Transfer Reactions

Macromolecules

The Transition Metals

The Main Group Elements

Nuclear Chemistry and Radiochemistry

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Exam 13: Kinetics: Mechanisms and Rates of Reactions

Why does the rate of a reaction generally slow with time?

For a large number of reactions in organic chemistry, an increase in temperature 10°C over room temperature will double the rate. What activation energy does this correspond to?

The reaction of NO2 with CO to give CO2 and NO can proceed through different mechanisms. What first step would be consistent with the following rate law?Rate = k[NO2][CO]

Which of the following are bimolecular processes? I. II. NO →\rarr→ ONNO III. H2C = CHCH3 + H2SO4 →\rarr→ CH3CH(OSO2(OH))CH3 IV. V. H2 →\rarr→ 2 H•

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H3O+(aq) + Cr2O72- + 6Fe2+(aq) →\rarr→ 2Cr3+(aq) + 21H2OWhat is the rate of increase of Cr3+ concentration expressed in terms of changing H3O+ concentration?

The reaction of NO with O2 to give oxygen is known to follow a third order rate law(rate = k[NO]2[O2]). Two possible mechanisms are shown below: Which of these two mechanisms is a more acceptable mechanism, based on the criteria given above?

It is determined that the charcoal in a fire pit used as an ancient hearth has lost about 42.3% of the initial 14C. How old was the fire pit if 14C has a half life of 5730 years?

At moderate temperatures, the rate law for the reaction of NO2 and CO to give CO2 and NO follows the rate law shown below:rate = k [NO2]2 In which flask will the reaction be faster and how much faster?

The reaction of NO2 with CO to give CO2 and NO can proceed through different mechanisms. What rate law would be consistent for the following first step? 2 NO2 →\rightarrow→ NO + NO3

Cyclohexane is manufactured from the reaction of benzene with hydrogen: C6H6(g) + 3 H2(g) →\rarr→ C6H12(g) If the initial concentration of hydrogen was 1.5 M and 5 minutes later the hydrogen concentration is 0.34 M, what is the average rate of appearance of cyclohexane?

Which of the following does NOT occur during a reaction facilitated by a heterogeneous catalyst?

The reaction A + 2B →\rarr→ products was found to have the rate law; rate = k[A] [B]2. While holding the concentration of A constant, the concentration of B was increased from 0.010M to 0.030M. Predict by what factor the rate of reaction will increase.

A 1.66 x 10-4 mole sample of 239Pu undergoes 9 x 107 decays per second obeying first-order kinetics. How many decays per second would be expected from a 5.46 x 10-1 mole sample?

Show that the mechanism and rate law are closely related.

A particular first-order reaction is characterized by activation energy of 50 kJ/mole. At what temperature would the rate of the reaction be 10 times that at 298oK?

Fundamental Concepts of Chemistry

The Behaviour of Gases

Energy and Its Conservation

Atoms and Light

Atomic Energies and Periodicity

Fundamentals of Chemical Bonding

Theories of Chemical Bonding

Effects of Intermolecular Forces

Properties of Solutions

Organic Chemistrystructure

Organic Chemistryreactions

Spontaneity of Chemical Processes

Principles of Chemical Equilibrium

Aqueous Acidbase Equilibria

Applications of Aqueous Equilibria

Electron Transfer Reactions

Macromolecules

The Transition Metals

The Main Group Elements

Nuclear Chemistry and Radiochemistry

Filters

The reaction of NO₂ with CO to give CO₂ and NO can proceed through different mechanisms. What first step would be consistent with the following rate law?Rate = k[NO₂][CO]

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H₃O⁺(aq) + Cr₂O₇^2-+ 6Fe²⁺(aq) $\rarr$ 2Cr³⁺(aq) + 21H₂OWhat is the rate of increase of Cr³⁺ concentration expressed in terms of changing H₃O⁺concentration?

The reaction of NO with O₂ to give oxygen is known to follow a third order rate law(rate = k[NO]²[O₂]). Two possible mechanisms are shown below: Which of these two mechanisms is a more acceptable mechanism, based on the criteria given above?

It is determined that the charcoal in a fire pit used as an ancient hearth has lost about 42.3% of the initial ¹⁴C. How old was the fire pit if ¹⁴C has a half life of 5730 years?

At moderate temperatures, the rate law for the reaction of NO₂ and CO to give CO₂ and NO follows the rate law shown below:rate = k [NO₂]² In which flask will the reaction be faster and how much faster?

The reaction of NO₂ with CO to give CO₂ and NO can proceed through different mechanisms. What rate law would be consistent for the following first step? 2 NO₂ $\rightarrow$ NO + NO₃

Cyclohexane is manufactured from the reaction of benzene with hydrogen: C₆H₆(g) + 3 H₂(g) $\rarr$ C₆H₁₂(g) If the initial concentration of hydrogen was 1.5 M and 5 minutes later the hydrogen concentration is 0.34 M, what is the average rate of appearance of cyclohexane?

The reaction A + 2B $\rarr$ products was found to have the rate law; rate = k[A] [B]². While holding the concentration of A constant, the concentration of B was increased from 0.010M to 0.030M. Predict by what factor the rate of reaction will increase.

A 1.66 x 10^-4 mole sample of ²³⁹Pu undergoes 9 x 10⁷ decays per second obeying first-order kinetics. How many decays per second would be expected from a 5.46 x 10^-1 mole sample?

A particular first-order reaction is characterized by activation energy of 50 kJ/mole. At what temperature would the rate of the reaction be 10 times that at 298^oK?