Question 1

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.What is the rate of reaction with respect to A over the time interval 700 to 800 seconds?

Accepted Answer

The slope of the concentration versus time graph represents the rate of reaction. Since the rate of reaction with respect to A is constant over the time interval 300 to 400 seconds, it can be assumed that the reaction is a first-order reaction with respect to A. Therefore, the rate of reaction with respect to A will be the same throughout the entire reaction, and thus the rate of reaction with respect to A over the time interval 700 to 800 seconds will be the same as the rate of reaction with respect to A over the time interval 300 to 400 seconds. Since the rate of reaction with respect to A over the time interval 300 to 400 seconds is 3.7 × 10^-5 M/s, the rate of reaction with respect to A over the time interval 700 to 800 seconds will be less than 3.7 × 10^-5 M/s (option B).

Question 2

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and an activation energy of 264 kJ/mol.What is the temperature of the reaction when the rate constant is equal to 4.36 × 10^-3 s^-1?

Accepted Answer

Using the Arrhenius equation, we can calculate the temperature when the rate constant is 4.36 × 10^-3 s^-1. Solving for the temperature gives approximately 540°C.

Question 3

Which of the following does not affect the rate of a bimolecular reaction?

Accepted Answer

All of the options listed (concentrations of reactants, presence of a catalyst, and temperature) affect the rate of a bimolecular reaction. Concentrations of reactants influence the frequency of collisions between molecules, the presence of a catalyst lowers the activation energy required for the reaction, and temperature affects the kinetic energy of the molecules, thus influencing the rate of reaction.

Question 4

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺ If the activation energy,E_a,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10^-3 min^-1,what is the frequency factor,A?

Accepted Answer

The frequency factor, A, can be calculated using the Arrhenius equation: k = A * e^(-Ea/RT). Rearranging for A gives A = k / e^(-Ea/RT). Substituting the given values (Ea = 126,000 J/mol, k = 9.8 × 10^-3 min^-1, R = 8.314 J/mol·K, T = 303 K), we find A ≈ 5 × 10^19 min^-1.

Question 5

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺ If the activation energy is 126 kJ/mol and frequency factor is 8.62 × 10¹⁷ s^-1,at what temperature is the rate constant equal to 3.63 × 10^-3 s^-1 for the first-order reaction?

Accepted Answer

The answer of The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes...

Question 6

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺ If the activation energy,E_a,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10^-3 min^-1,what is the rate constant at 50°C?

Accepted Answer

To find the rate constant at 50°C, we can use the Arrhenius equation which relates temperature, activation energy, and rate constant:

k2 = k1 * exp[(Ea/R) * ((1/T1) - (1/T2))]

where k1 is the rate constant at 30°C, k2 is the rate constant at 50°C, Ea is the activation energy, R is the gas constant (8.314 J/mol*K), T1 is the temperature at 30°C (303 K), and T2 is the temperature at 50°C (323 K).

Plugging in the given values, we get:

k2 = (9.8 × 10^-3 min^-1) * exp[(126000 J/mol / (8.314 J/mol*K)) * ((1/303 K) - (1/323 K))]

k2 = 2.2 × 10^-1 min^-1

Therefore, the answer is B.

Question 7

When the concentration of A is doubled,the rate for the reaction: 2 A + B → 2 C quadruples. When the concentration of B is doubled the rate remains the same.Which mechanism below is consistent with the experimental observations?

Accepted Answer

The rate-determining step is the slow step, which involves only A, consistent with the rate quadrupling when A is doubled. B does not appear in the slow step, so doubling B does not affect the rate.

Question 8

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl₂→ 2 Cl (fast,equilibrium) Step 2: Cl + CO → COCl (fast,equilibrium) Step 3: COCl + Cl₂ → COCl₂ + Cl (slow) What is the molecularity of the rate-determining step?

Accepted Answer

The rate-determining step is Step 3, which involves the collision of COCl and Cl₂. As two molecules are colliding in this step, it is a bimolecular reaction.

Question 9

Which of the following statements are true about reaction mechanisms? I.A rate law can be written from the molecularity of the slowest elementary step.
II.The final rate law can include intermediates.
III.The rate of the reaction is dependent on the fastest step in the mechanism.
IV.A mechanism can never be proven to be the correct pathway for a reaction.

Accepted Answer

I. True, because the rate law is determined by the slowest step, also known as the rate-determining step, which dictates the overall reaction rate. IV. True, because while mechanisms can be supported by experimental evidence, they cannot be definitively proven as the only pathway for a reaction; there may always be alternative pathways or mechanisms that have not been considered or discovered.

Question 10

The elementary reaction representing the formation of ozone: O₂(g)+ O(g)+ M(g)→ O₃(g)+ M^*(g)is an example of a ________ reaction.

Accepted Answer

This reaction involves the collision of three molecules: one O3 molecule, one O molecule, and one M molecule. Therefore, it is a termolecular reaction.

Question 11

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g) Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g) What is the molecularity of the overall reaction?

Accepted Answer

Molecularity refers to the number of molecules participating in an elementary step of a reaction, not the overall reaction.

Question 12

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Br + O₃ → BrO + O₂ BrO + O → Br + O₂ Which species is a catalyst in this mechanism?

Accepted Answer

Br acts as a catalyst because it is consumed in the first step and regenerated in the second step, without being consumed in the overall reaction.

Question 13

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and 5.70 × 10^-4 s^-1 at 500°C.What is the activation energy,E_a,for the reaction?

Accepted Answer

The answer of The first-order isomerization reaction: cyclopropane → propene,has...

Question 14

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to C,Δ[C]/Δt?

Accepted Answer

The rate of reaction with respect to a reactant or product is dependent on the stoichiometry of the reaction. If the stoichiometry indicates that C is produced or consumed at half the rate of A, and if A is consumed (indicated by a positive rate), then C would be produced at half that rate, but since it's being produced (not consumed), the rate would be negative, indicating an increase in [C] over time.

Question 15

A suggested mechanism for the decomposition of peroxide (H₂O₂)is H₂O₂ (aq)2OH (aq) H₂O₂ (aq)+ OH (aq)H₂O (l)+ HO₂ (g) HO₂ (g)+ OH (aq)H₂O (l)+ O₂ (g) Which of the following correctly labels the chemical equation for the overall reaction and the reaction intermediates?

Accepted Answer

The overall reaction is the decomposition of peroxide into water and oxygen gas, which is correctly labeled as 2H₂O₂ (aq) → 2H₂O (l) + O₂ (g). The two intermediates in the mechanism are labeled correctly as HO₂ (g) + OH (aq) → H₂O (l) + O₂ (g) and H₂O₂ (aq) + OH (aq) → HO₂ (g) + H₂O (l). Therefore, choice C is the best choice as it correctly labels both the overall reaction and the intermediates.

Question 16

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Step 1: Br + O₃ → BrO + O₂ Step 2: BrO + O → Br + O₂ Which species is an intermediate in this mechanism?

Accepted Answer

An intermediate is a species that is formed in one step of a reaction mechanism and then consumed in a later step. In this mechanism, BrO is formed in Step 1 and consumed in Step 2, making it an intermediate. Br and O are reactants and products, respectively, and O₃ is a catalyst that does not appear in the overall reaction.

Question 17

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g) Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g) Which species is a catalyst?

Accepted Answer

A catalyst is a substance that speeds up a reaction without being consumed in the process. In Step 1 of the mechanism, HO reacts with O₃ to form HO₂ and O₂, but then HO₂ is able to react with O in Step 2 to reform HO and O₂. The HO is consumed in the first step but then regenerated in the second step, so it acts as a catalyst for the overall reaction.

Question 18

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to B,Δ[B]/Δt?

Accepted Answer

According to the Law of Mass Action, the rate of a chemical reaction is directly proportional to the concentrations of the reactants involved. Therefore, if the rate of reaction with respect to A is known, the rate of reaction with respect to B can be determined using the stoichiometry of the reaction. From the plot, it appears that the reaction involves 1 mole of A and 4 moles of B. Therefore, the rate of reaction with respect to B can be calculated as (1/4)(Δ[A]/Δt). Substituting the given value for Δ[A]/Δt, we get Δ[B]/Δt = (1/4)(3.7 × 10^-5 M/s) = 9.2 × 10^-6 M/s. Therefore, the best choice is B.

Question 19

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. 
-Which equation best represents the reaction?

Accepted Answer

The concentration of gas C decreases and the concentration of gas A and B increase as time passes. This is consistent with the reaction: 2C(g) → 4A(g) + B(g). Two moles of gas C are consumed for every mole of gas B, and four moles of gas A are produced for every mole of gas C. This matches the trend observed in the concentration versus time plot.

Question 20

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g) Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g) Which species is an intermediate?

Accepted Answer

The species HO₂ is an intermediate because it is formed in the first step of the mechanism and then consumed in the second step to regenerate O₂. HO and O are not intermediates because they are reactants or products throughout the mechanism. O₃ is not an intermediate because it is only present as a reactant in the first step and not involved in the second step.

Quiz 13: Chemical Kinetics

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.What is the rate of reaction with respect to A over the time interval 700 to 800 seconds?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and an activation energy of 264 kJ/mol.What is the temperature of the reaction when the rate constant is equal to 4.36 × 10^-3 s^-1?

Which of the following does not affect the rate of a bimolecular reaction?

When the concentration of A is doubled,the rate for the reaction: 2 A + B → 2 C quadruples. When the concentration of B is doubled the rate remains the same.Which mechanism below is consistent with the experimental observations?

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl₂→ 2 Cl (fast,equilibrium) Step 2: Cl + CO → COCl (fast,equilibrium) Step 3: COCl + Cl₂ → COCl₂ + Cl (slow) What is the molecularity of the rate-determining step?

The elementary reaction representing the formation of ozone: O₂(g) + O(g) + M(g) → O₃(g) + M^*(g) is an example of a ________ reaction.

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) What is the molecularity of the overall reaction?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Br + O₃ → BrO + O₂ BrO + O → Br + O₂ Which species is a catalyst in this mechanism?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and 5.70 × 10^-4 s^-1 at 500°C.What is the activation energy,E_a,for the reaction?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to C,Δ[C]/Δt?

A suggested mechanism for the decomposition of peroxide (H₂O₂) is H₂O₂ (aq) 2OH (aq) H₂O₂ (aq) + OH (aq) H₂O (l) + HO₂ (g) HO₂ (g) + OH (aq) H₂O (l) + O₂ (g) Which of the following correctly labels the chemical equation for the overall reaction and the reaction intermediates?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Step 1: Br + O₃ → BrO + O₂ Step 2: BrO + O → Br + O₂ Which species is an intermediate in this mechanism?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) Which species is a catalyst?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to B,Δ[B]/Δt?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Which equation best represents the reaction?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) Which species is an intermediate?

Quiz 13: Chemical Kinetics

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10-5 M/s.What is the rate of reaction with respect to A over the time interval 700 to 800 seconds?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10-4 s -1 at 470°C and an activation energy of 264 kJ/mol.What is the temperature of the reaction when the rate constant is equal to 4.36 × 10-3 s-1?

Which of the following does not affect the rate of a bimolecular reaction?

The aquation of tris(1,10-phenanthroline) iron(II) in acid solution takes place according to the equation: Fe(phen) 32+ + 3 H3O+ + 3 H2O → Fe(H2O) 62+ + 3 phenH+ If the activation energy,Ea,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10-3 min-1,what is the frequency factor,A?

The aquation of tris(1,10-phenanthroline) iron(II) in acid solution takes place according to the equation: Fe(phen) 32+ + 3 H3O+ + 3 H2O → Fe(H2O) 62+ + 3 phenH+ If the activation energy,Ea,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10-3 min-1,what is the rate constant at 50°C?

When the concentration of A is doubled,the rate for the reaction: 2 A + B → 2 C quadruples. When the concentration of B is doubled the rate remains the same.Which mechanism below is consistent with the experimental observations?

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl2→ 2 Cl (fast,equilibrium) Step 2: Cl + CO → COCl (fast,equilibrium) Step 3: COCl + Cl2 → COCl2 + Cl (slow) What is the molecularity of the rate-determining step?

The elementary reaction representing the formation of ozone: O2(g) + O(g) + M(g) → O3(g) + M*(g) is an example of a ________ reaction.

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O3(g) + HO(g) → HO2(g) + O2(g) Step 2: HO2(g) + O(g) → HO(g) + O2(g) What is the molecularity of the overall reaction?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Br + O3 → BrO + O2 BrO + O → Br + O2 Which species is a catalyst in this mechanism?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10-4 s-1 at 470°C and 5.70 × 10-4 s-1 at 500°C.What is the activation energy,Ea,for the reaction?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10-5 M/s.Over the same time interval what is the rate of reaction with respect to C,Δ[C]/Δt?

A suggested mechanism for the decomposition of peroxide (H2O2) is H2O2 (aq) 2OH (aq) H2O2 (aq) + OH (aq) H2O (l) + HO2 (g) HO2 (g) + OH (aq) H2O (l) + O2 (g) Which of the following correctly labels the chemical equation for the overall reaction and the reaction intermediates?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Step 1: Br + O3 → BrO + O2 Step 2: BrO + O → Br + O2 Which species is an intermediate in this mechanism?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O3(g) + HO(g) → HO2(g) + O2(g) Step 2: HO2(g) + O(g) → HO(g) + O2(g) Which species is a catalyst?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10-5 M/s.Over the same time interval what is the rate of reaction with respect to B,Δ[B]/Δt?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Which equation best represents the reaction?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O3(g) + HO(g) → HO2(g) + O2(g) Step 2: HO2(g) + O(g) → HO(g) + O2(g) Which species is an intermediate?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.What is the rate of reaction with respect to A over the time interval 700 to 800 seconds?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and an activation energy of 264 kJ/mol.What is the temperature of the reaction when the rate constant is equal to 4.36 × 10^-3 s^-1?

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl₂→ 2 Cl (fast,equilibrium) Step 2: Cl + CO → COCl (fast,equilibrium) Step 3: COCl + Cl₂ → COCl₂ + Cl (slow) What is the molecularity of the rate-determining step?

The elementary reaction representing the formation of ozone: O₂(g) + O(g) + M(g) → O₃(g) + M^*(g) is an example of a ________ reaction.

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) What is the molecularity of the overall reaction?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Br + O₃ → BrO + O₂ BrO + O → Br + O₂ Which species is a catalyst in this mechanism?

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and 5.70 × 10^-4 s^-1 at 500°C.What is the activation energy,E_a,for the reaction?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to C,Δ[C]/Δt?

A suggested mechanism for the decomposition of peroxide (H₂O₂) is H₂O₂ (aq) 2OH (aq) H₂O₂ (aq) + OH (aq) H₂O (l) + HO₂ (g) HO₂ (g) + OH (aq) H₂O (l) + O₂ (g) Which of the following correctly labels the chemical equation for the overall reaction and the reaction intermediates?

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Step 1: Br + O₃ → BrO + O₂ Step 2: BrO + O → Br + O₂ Which species is an intermediate in this mechanism?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) Which species is a catalyst?

Shown is a concentration versus time plot for a reaction involving gases A,B,and C. -Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to B,Δ[B]/Δt?

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g) + HO(g) → HO₂(g) + O₂(g) Step 2: HO₂(g) + O(g) → HO(g) + O₂(g) Which species is an intermediate?