Question 1

For a reaction with a second order rate constant,the correct unit is M ∙ time-1.

Accepted Answer

A) True 
 B)False

Question 2

What is the rate law for the following reaction and its mechanism?
2 HgCl2 + C2O42- → 2 Cl- + 2 CO2 + Hg2Cl2 (overall reaction)
HgCl2 + C2O42- ⇌ HgCl2C2O42- (fast)
HgCl2C2O42- + C2O42- → Hg + 2 C2O4Cl2- (slow)
Hg + HgCl2 → Hg2Cl2 (fast)
2 C2O4Cl2- → C2O42- + 2Cl- + 2 CO2 (fast)

Accepted Answer

A) Rate = k[HgCl2][C2O42-] 
B) Rate = k[HgCl2]2[C2O42-] 
C) Rate = k[Hg2Cl2] 
D) Rate = k[HgCl2][C2O42-]2  
E) Rate = k[HgCl2]2[C2O42-]2  
A) Rate = k[HgCl2][C2O42-] 
B) Rate = k[HgCl2]2[C2O42-] 
C) Rate = k[Hg2Cl2] 
D) Rate = k[HgCl2][C2O42-]2  
E) Rate = k[HgCl2]2[C2O42-]2

Question 3

For a particular first-order reaction,it takes 24 minutes for the concentration of the reactant to decrease to 25% of its initial value.What is the value for rate constant (in s-1)for the reaction?

Accepted Answer

A) 2.0 × 10-4 s-1 
B) 9.6 × 10-4 s-1 
C) 1.2 × 10-2 s-1 
D) 5.8 × 10-2 s-1 
A) 2.0 × 10-4 s-1 
B) 9.6 × 10-4 s-1 
C) 1.2 × 10-2 s-1 
D) 5.8 × 10-2 s-1

Question 4

In the Arrhenius equation,ln k = -Ea/RT + ln A,the symbol A is a constant that represents the frequency of collisions with the proper orientation and other steric conditions favorable for a reaction.

Accepted Answer

A) True 
 B)False

Question 5

The rate constant,k,for a first-order reaction is equal to 4.2 × 10-4 s-1.What is the half-life for the reaction?

Accepted Answer

A) 2.9 × 10-4 s 
B) 1.2 × 103 s 
C) 1.7 × 103 s 
D) 2.4 × 103 s 
A) 2.9 × 10-4 s 
B) 1.2 × 103 s 
C) 1.7 × 103 s 
D) 2.4 × 103 s

Question 6

If the rate of a specific chemical reaction is independent of the concentrations of the reactants,the reaction is zero order.

Accepted Answer

A) True 
 B)False

Question 7

The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g)→ 4 NO2(g)+ O2(g).
If the rate of appearance of O2 is equal to 3.00 mol min-1 at a particular moment,what is the rate of disappearance of N2O5 at that moment?

Accepted Answer

A) 0.750 mol min-1 
B) 1.50 mol min-1 
C) 6.00 mol min-1 
D) 12.0 mol min-1 
A) 0.750 mol min-1 
B) 1.50 mol min-1 
C) 6.00 mol min-1 
D) 12.0 mol min-1

Question 8

The rate constant for a first-order reaction is k = 0.00073 s-1.Determine the percent of reactant that has decomposed after 500 s.

Accepted Answer

A) 69% 
B) 57% 
C) 37% 
D) 31% 
E) 43% 
A) 69% 
B) 57% 
C) 37% 
D) 31% 
E) 43%

Question 9

What is the rate law for the following mechanism?
CH3COOC2H5 + H2O → CH3COOC2H6+ + OH- (slow)
CH3COOC2H6+ → CH3COOH + C2H5+ (fast)
C2H5+ + OH- → C2H5OH (fast)

Accepted Answer

A) Rate = k[CH3COOC2H5][H2O]2  
B) Rate = k[C2H5OH] 
C) Rate = k[CH3COOH] 
D) Rate = k[CH3COOC2H5] 
E) Rate = k[CH3COOC2H5][H2O] 
A) Rate = k[CH3COOC2H5][H2O]2  
B) Rate = k[C2H5OH] 
C) Rate = k[CH3COOH] 
D) Rate = k[CH3COOC2H5] 
E) Rate = k[CH3COOC2H5][H2O]

Question 10

The reaction 2 H2 + NO → H2O + 1/2N2 is first order in H2 and second order in NO.The rate law is ________.

Accepted Answer

A) k[H2]2[NO] 
B) k[H2][NO]2  
C) k[H2] 
D) k[H2][NO] 
E) k[H2][NO]-2  
A) k[H2]2[NO] 
B) k[H2][NO]2  
C) k[H2] 
D) k[H2][NO] 
E) k[H2][NO]-2

Question 11

Temperature has no effect on reaction rate.

Accepted Answer

A) True 
 B)False

Question 12

The isomerization of methylisonitrile to acetonitrile 
  NC(g)→   CN(g) 
Is first order in   NC.The rate constant for the reaction is 9.45 × 10-5   At 478 K.The   Of the reaction when the initial [   NC] is 0.030 mol L-1 is ________ s.

Accepted Answer

A) 1.06 × 104 
B) 5.29 × 103 
C) 3.53E × 105 
D) 7.33 × 103 
E) 1.36 × 10-4 
A) 1.06 × 104 
B) 5.29 × 103 
C) 3.53E × 105 
D) 7.33 × 103 
E) 1.36 × 10-4

Question 13

If the half-life of a reactant is independent of its initial concentration,the reaction order is ________.

Accepted Answer

A) 0 
B) 0.5 
C) 1 
D) 2 
E) 3 
A) 0 
B) 0.5 
C) 1 
D) 2 
E) 3

Question 14

A particular first-order reaction has a rate constant of 1.35 ×     At 25.0 °C.What is the magnitude of k at 75.0 °C if

Accepted Answer

A) 3.47 ×   s-1 
B) 1.92 × 104 s-1 
C) 670 s-1 
D) 3.85 ×   s-1 
E) 1.36 ×   s-1 
A) 3.47 ×   s-1 
B) 1.92 × 104 s-1 
C) 670 s-1 
D) 3.85 ×   s-1 
E) 1.36 ×   s-1

Question 15

A catalyst:
I.lowers activation energy
II.provides an alternate reaction pathway
III.is consumed in the reaction and therefore does not appear in the chemical equation of each mechanism
IV.speeds a reaction
V.is heterogeneous if it is in a different phase than the reactants

Accepted Answer

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

Question 16

Which of the following lowers the activation energy of a reaction?

Accepted Answer

A) adding reactants 
B) lowering the temperature 
C) removing products 
D) adding a catalyst 
E) raising the temperature 
A) adding reactants 
B) lowering the temperature 
C) removing products 
D) adding a catalyst 
E) raising the temperature

Question 17

The second-order reaction 2 Mn(CO)5 → Mn2(CO)10 has a rate constant equal to 3.0 × 109 L mol-1 s-1 at 25 °C.If the initial concentration of Mn(CO)5 is 2.0 × 10-5 mol L-1,how long will it take for 90.% of the reactant to disappear?

Accepted Answer

A) 6.7 × 10-16 s 
B) 7.4 × 10-15 s 
C) 1.5 × 10-4 s 
D) 6.0 × 103 s 
A) 6.7 × 10-16 s 
B) 7.4 × 10-15 s 
C) 1.5 × 10-4 s 
D) 6.0 × 103 s

Question 18

The rate of a specific chemical reaction is independent of the concentrations of the reactants.Thus the reaction is:

Accepted Answer

A) first order in A 
B) second order 
C) first order in the product 
D) catalyzed 
E) overall zero order 
A) first order in A 
B) second order 
C) first order in the product 
D) catalyzed 
E) overall zero order

Question 19

The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g)→ 4 NO2(g)+ O2(g).
If the rate of appearance of NO2 is equal to 0.560 mol min-1 at a particular moment,what is the rate of appearance of O2 at that moment?

Accepted Answer

A) 0.140 mol min-1 
B) 0.280 mol min-1 
C) 1.12 mol min-1 
D) 2.24 mol min-1 
A) 0.140 mol min-1 
B) 0.280 mol min-1 
C) 1.12 mol min-1 
D) 2.24 mol min-1

Question 20

For the reaction: 2 N2O5(g)→ 4 NO2(g)+ O2(g)the rate law is: 
 = k[N2O5]
At 300 K,the half-life is 2.50 × 104 seconds and the activation energy is 103.3 kJ/mol.At what temperature is the half-life 400.seconds?

Accepted Answer

A) 273 K 
B) 333 K 
C) 3.04 K 
D) 304 K 
E) 296 K 
A) 273 K 
B) 333 K 
C) 3.04 K 
D) 304 K 
E) 296 K

Exam 20: Chemical Kinetics

For a reaction with a second order rate constant,the correct unit is M ∙ time-1.

What is the rate law for the following reaction and its mechanism? 2 HgCl2 + C2O42- → 2 Cl- + 2 CO2 + Hg2Cl2 (overall reaction) HgCl2 + C2O42- ⇌ HgCl2C2O42- (fast) HgCl2C2O42- + C2O42- → Hg + 2 C2O4Cl2- (slow) Hg + HgCl2 → Hg2Cl2 (fast) 2 C2O4Cl2- → C2O42- + 2Cl- + 2 CO2 (fast)

For a particular first-order reaction,it takes 24 minutes for the concentration of the reactant to decrease to 25% of its initial value.What is the value for rate constant (in s-1)for the reaction?

In the Arrhenius equation,ln k = -Ea/RT + ln A,the symbol A is a constant that represents the frequency of collisions with the proper orientation and other steric conditions favorable for a reaction.

The rate constant,k,for a first-order reaction is equal to 4.2 × 10-4 s-1.What is the half-life for the reaction?

If the rate of a specific chemical reaction is independent of the concentrations of the reactants,the reaction is zero order.

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N2O5(g)→ 4 NO2(g)+ O2(g). If the rate of appearance of O2 is equal to 3.00 mol min-1 at a particular moment,what is the rate of disappearance of N2O5 at that moment?

The rate constant for a first-order reaction is k = 0.00073 s-1.Determine the percent of reactant that has decomposed after 500 s.

What is the rate law for the following mechanism? CH3COOC2H5 + H2O → CH3COOC2H6+ + OH- (slow) CH3COOC2H6+ → CH3COOH + C2H5+ (fast) C2H5+ + OH- → C2H5OH (fast)

The reaction 2 H2 + NO → H2O + 1/2N2 is first order in H2 and second order in NO.The rate law is ________.

Temperature has no effect on reaction rate.

The isomerization of methylisonitrile to acetonitrile NC(g)→ CN(g) Is first order in NC.The rate constant for the reaction is 9.45 × 10-5 At 478 K.The Of the reaction when the initial [ NC] is 0.030 mol L-1 is ________ s.

If the half-life of a reactant is independent of its initial concentration,the reaction order is ________.

A particular first-order reaction has a rate constant of 1.35 × At 25.0 °C.What is the magnitude of k at 75.0 °C if

A catalyst: I.lowers activation energy II.provides an alternate reaction pathway III.is consumed in the reaction and therefore does not appear in the chemical equation of each mechanism IV.speeds a reaction V.is heterogeneous if it is in a different phase than the reactants

Which of the following lowers the activation energy of a reaction?

The second-order reaction 2 Mn(CO)5 → Mn2(CO)10 has a rate constant equal to 3.0 × 109 L mol-1 s-1 at 25 °C.If the initial concentration of Mn(CO)5 is 2.0 × 10-5 mol L-1,how long will it take for 90.% of the reactant to disappear?

The rate of a specific chemical reaction is independent of the concentrations of the reactants.Thus the reaction is:

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N2O5(g)→ 4 NO2(g)+ O2(g). If the rate of appearance of NO2 is equal to 0.560 mol min-1 at a particular moment,what is the rate of appearance of O2 at that moment?

For the reaction: 2 N2O5(g)→ 4 NO2(g)+ O2(g)the rate law is: = k[N2O5] At 300 K,the half-life is 2.50 × 104 seconds and the activation energy is 103.3 kJ/mol.At what temperature is the half-life 400.seconds?

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For a reaction with a second order rate constant,the correct unit is M ∙ time^-¹.

For a particular first-order reaction,it takes 24 minutes for the concentration of the reactant to decrease to 25% of its initial value.What is the value for rate constant (in s^-1)for the reaction?

In the Arrhenius equation,ln k = ^-^E_a/RT + ln A,the symbol A is a constant that represents the frequency of collisions with the proper orientation and other steric conditions favorable for a reaction.

The rate constant,k,for a first-order reaction is equal to 4.2 × 10^-4 s^-1.What is the half-life for the reaction?

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g). If the rate of appearance of O₂ is equal to 3.00 mol min^-1 at a particular moment,what is the rate of disappearance of N₂O₅ at that moment?

The rate constant for a first-order reaction is k = 0.00073 s^-1.Determine the percent of reactant that has decomposed after 500 s.

What is the rate law for the following mechanism? CH₃COOC₂H₅ + H₂O → CH₃COOC₂H₆⁺ + OH^- (slow) CH₃COOC₂H₆⁺ → CH₃COOH + C₂H₅⁺ (fast) C₂H₅⁺ + OH^- → C₂H₅OH (fast)

The reaction 2 H₂ + NO → H₂O + 1/2N₂ is first order in H₂ and second order in NO.The rate law is ________.

The isomerization of methylisonitrile to acetonitrile NC(g)→ CN(g) Is first order in NC.The rate constant for the reaction is 9.45 × 10^-5 At 478 K.The Of the reaction when the initial [ NC] is 0.030 mol L^-1 is ________ s.

The second-order reaction 2 Mn(CO)₅ → Mn₂(CO)₁₀ has a rate constant equal to 3.0 × 10⁹ L mol^-1 s^-1 at 25 °C.If the initial concentration of Mn(CO)₅ is 2.0 × 10^-5 mol L^-1,how long will it take for 90.% of the reactant to disappear?

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g). If the rate of appearance of NO₂ is equal to 0.560 mol min^-1 at a particular moment,what is the rate of appearance of O₂ at that moment?

For the reaction: 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g)the rate law is: = k[N₂O₅] At 300 K,the half-life is 2.50 × 10⁴ seconds and the activation energy is 103.3 kJ/mol.At what temperature is the half-life 400.seconds?