DP Chemistry (last assessment 2024)

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Additional higher level (AHL) » Topic 16: Chemical kinetics

Topic 16: Chemical kinetics

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Directly related questions

23M.1.HL.TZ1.14:

What is the enthalpy change for the following reaction?

CH₄ (g) + H₂O (g) → CO (g) + 3H₂ (g)

Reaction	ΔH^⦵
2C_(graphite) + O₂ (g) → 2CO (g)	−222 kJ mol⁻¹
C_(graphite) + 2H₂ (g) → CH₄ (g)	−74 kJ mol⁻¹
2H2 (g) + O₂ (g) → 2H₂O (g)	−484 kJ mol⁻¹

A. −74 − 242 + 111

B. +74 + 242 − 111

C. −74 − 484 − 222

D. +74 + 484 − 222

23M.1.HL.TZ1.14:

What is the enthalpy change for the following reaction?

CH₄ (g) + H₂O (g) → CO (g) + 3H₂ (g)

Reaction	ΔH^⦵
2C_(graphite) + O₂ (g) → 2CO (g)	−222 kJ mol⁻¹
C_(graphite) + 2H₂ (g) → CH₄ (g)	−74 kJ mol⁻¹
2H2 (g) + O₂ (g) → 2H₂O (g)	−484 kJ mol⁻¹

A. −74 − 242 + 111

B. +74 + 242 − 111

C. −74 − 484 − 222

D. +74 + 484 − 222

Sub sections and their related questions

16.1 Rate expression and reaction mechanism

17N.1.hl.TZ0.21:
The rate expression for the reaction X (g) + 2Y (g) → 3Z (g) is

rate = k[X]⁰ [Y]²

By which factor will the rate of reaction increase when the concentrations of X and Y are both increased by a factor of 3?

A. 6

B. 9

C. 18

D. 27
17N.1.hl.TZ0.22: Which pair of statements explains the increase in rate of reaction when the temperature...
17N.2.hl.TZ0.2e.i: Deduce the order of reaction with respect to Cl2 and NO.
17N.2.hl.TZ0.2e.ii:
State the rate expression for the reaction.
17N.2.hl.TZ0.2e.iii: Calculate the value of the rate constant at 263 K.
18M.1.hl.TZ1.19: What are correct labels for the Maxwell−Boltzmann energy distribution curves?
18M.1.hl.TZ1.20: The reaction between NO2 and F2 gives the following rate data at a certain temperature. What...
18M.2.hl.TZ1.4b.iv:
Deduce the rate expression for the reaction.
18M.2.hl.TZ1.4b.v:
Calculate the rate constant of the reaction, stating its units.
18M.1.hl.TZ2.20: When X reacts with Y to give Z, the following graph is plotted. What can be deduced from the...
18M.1.hl.TZ2.21: Which statement is correct? A. The value of the rate constant, k, is independent of...
18N.1.hl.TZ0.20: Compounds X and Y were mixed and the time taken for a colour to appear was recorded at various...
18N.1.hl.TZ0.21:
The rate expression for the reaction is: rate = k [NO]²[O₂].

2NO (g) + O₂ (g) → 2NO₂ (g)

Which mechanism is not consistent with this rate expression?
18N.2.hl.TZ0.10a: Classify substances B and D as reactant, product, catalyst, or intermediate, based on the...
18N.2.hl.TZ0.10b:
Deduce the rate expression.
18N.2.hl.TZ0.10c: Calculate the initial rate of reaction for experiment 2, if measured under the same conditions.
19M.2.hl.TZ1.4b(ii):
Two more trials (2 and 3) were carried out. The results are given below.

Determine the rate equation for the reaction and its overall order, using your answer from (b)(i).

Rate equation:

Overall order:
19M.2.hl.TZ2.2c(i):
Deduce how the rate of reaction at t = 2 would compare to the initial rate.
19M.2.hl.TZ2.2c(ii):
It has been suggested that the reaction occurs as a two-step process:

Step 1: N₂O (g) → N₂ (g) + O (g)

Step 2: N₂O (g) + O (g) → N₂ (g) + O₂ (g)

Explain how this could support the observed rate expression.
19M.1.hl.TZ1.20: Which graph is obtained from a first order reaction?
19M.1.hl.TZ1.21: Which is correct for the reaction mechanism shown?
19M.1.hl.TZ2.20:
Which statement is correct about a catalyst?

A. It decreases the activation energy of the forward reaction but not the reverse.

B. It increases the proportion of products to reactants in an equilibrium.

C. It decreases the enthalpy change of the reaction.

D. It changes the mechanism of the reaction.
19M.1.hl.TZ2.21:
What is the order with respect to each reactant?

2NO (g) + Cl₂ (g) → 2NOCl (g)
19N.2.hl.TZ0.1e(i): Identify the steps which absorb ultraviolet light.
19N.2.hl.TZ0.3b(i):
Determine the rate expression from the results, explaining your method.
19N.1.hl.TZ0.21: Which is correct?
20N.1.hl.TZ0.20:
What are the units of the rate constant, $k$ , if the rate equation is $Rate = k [A] {[B]}^{2}$ ?

A.   $mol {dm}^{- 3} s^{- 1}$

B.   ${dm}^{3} {mol}^{- 1} s^{- 1}$

C.   ${dm}^{6} {mol}^{- 2} s^{- 1}$

D.   ${dm}^{9} {mol}^{- 3} s^{- 1}$
20N.1.hl.TZ0.21:
Which graph represents the relationship between the rate constant, $k$ , and temperature, $T$ , in kelvin?
21M.1.hl.TZ1.20:
A reaction proceeds by the following mechanism:

step 1: $A + A \to B$
step 2: $B + C \to D$

Which rate equation is consistent with this mechanism?

A. Rate = k[B]²[C]

B. Rate = k[A]²[B][C]

C. Rate = k[A]²

D. Rate = k[A][C]
21M.1.hl.TZ1.21: Which graphs show a first order reaction? A. V and X B. V and Y C. W and X D. W and Y
21M.1.hl.TZ2.20: Which graph represents a second order reaction with respect to X? X → Y
21M.2.hl.TZ1.6b(iii):
Write the rate expression for this reaction.
21M.2.hl.TZ1.6b(iv):
Calculate the value of the rate constant, k, giving its units.
21M.2.hl.TZ1.7c:
Explain, using equations, how the presence of ${CCl}_{2} F_{2}$ results in a chain reaction that decreases the concentration of ozone in the stratosphere.
21M.2.hl.TZ2.6a:
Determine the rate expression for the reaction.
21M.2.hl.TZ2.6b:
Determine the value and unit of the rate constant using the rate expression in (a).
21N.1.hl.TZ0.20: Which graph shows a first order reaction?
21N.1.hl.TZ0.21:
The rate equation for a reaction is:

rate = k[A][B]

Which mechanism is consistent with this rate equation?

A. 2A $⇌$ I Fast
I + B → P Slow

B. A + B $⇌$ I Fast
I + A → P Slow

C. A → I Slow
I + B → P Fast

D. B $⇌$ I Fast
I + A → P Slow
21N.2.hl.TZ0.10c(i):
Deduce the rate expression for this reaction.
21N.2.hl.TZ0.10c(ii): Deduce the units of the rate constant.
21N.2.hl.TZ0.10c(iii):
Determine the initial rate of reaction in experiment 4.
21N.2.hl.TZ0.10d: Deduce, with a reason, the mechanism of the reaction between 2-chloropentane and sodium hydroxide.
22M.1.hl.TZ1.20: The table shows data for the hydrolysis of a halogenoalkane, RCl. Which statements are...
22M.1.hl.TZ1.21:
What is the activation energy according to the following plot of the linear form of the Arrhenius equation?

Arrhenius equation: $k = A e^{\frac{- E a}{R T}}$ .

A. $E_{a} = \frac{2 \times 8.31}{0.06}$

B. $E_{a} = \frac{- 2 \times 8.31}{0.06}$

C. $E_{a} = e^{\frac{2 \times 8.31}{0.06}}$

D. $E_{a} = e^{\frac{- 2 \times 8.31}{0.06}}$
22M.1.hl.TZ2.19:
What is correct about the rate of disappearance of NO?

2NO (g) + 2H₂(g) → N₂(g) + 2H₂O (g)

rate = k[H₂][NO]²

A. It equals half the rate of disappearance of H₂.

B. It equals the rate of disappearance of H₂.

C. It equals twice the rate of disappearance of H₂.

D. It equals four times the rate of disappearance of H₂.
22M.1.hl.TZ2.20: Which energy profile diagram represents an exothermic SN1 reaction?
22M.2.hl.TZ1.2c(i):
Use the graph to deduce the dependence of the reaction rate on the amount of Mg.
22M.2.hl.TZ1.2c(ii):
The reaction is first order with respect to HCl. Calculate the time taken, in seconds (s), for half of the Mg to dissolve when [HCl] = 0.5 mol dm^–3.
22M.2.hl.TZ2.4a(i):
Deduce the order of reaction with respect to hydrogen.
22M.2.hl.TZ2.4a(ii):
Deduce the rate expression for the reaction.
22M.2.hl.TZ2.4a(iii):
Calculate the value of the rate constant stating its units.
22N.1.hl.TZ0.20:
Data is given for the reaction 2X₂ (g) + Y₂ (g) → 2X₂Y (g).

What rate equation can be inferred from the data?

A. Rate = k [X₂] [Y₂]

B. Rate = k [X₂]² [Y₂]

C. Rate = k [X₂]² [Y₂]⁰

D. Rate = k [X₂]² [Y₂]²
22N.1.hl.TZ0.21:
The activation energy of a reaction can be obtained from the rate constant, k, and the absolute temperature, $T$ . Which graph of these quantities produces a straight line?

A. k against $T$

B. k against $\frac{1}{T}$

C. ln k against $T$

D. ln k against $\frac{1}{T}$
22N.2.hl.TZ0.6a:
This reaction could proceed through either S_N1 or S_N2 mechanisms depending on the reaction conditions. Sketch a graph of the rate versus nucleophile concentration, [CN⁻], for each of the mechanisms.

23M.1.HL.TZ1.14:

What is the enthalpy change for the following reaction?

CH₄ (g) + H₂O (g) → CO (g) + 3H₂ (g)

Reaction	ΔH^⦵
2C_(graphite) + O₂ (g) → 2CO (g)	−222 kJ mol⁻¹
C_(graphite) + 2H₂ (g) → CH₄ (g)	−74 kJ mol⁻¹
2H2 (g) + O₂ (g) → 2H₂O (g)	−484 kJ mol⁻¹

A. −74 − 242 + 111

B. +74 + 242 − 111

C. −74 − 484 − 222

D. +74 + 484 − 222

19M.2.hl.TZ1.4b(ii):
Two more trials (2 and 3) were carried out. The results are given below.

Determine the rate equation for the reaction and its overall order, using your answer from (b)(i).

Rate equation:

Overall order:
19M.2.hl.TZ1.b(ii):
Two more trials (2 and 3) were carried out. The results are given below.

Determine the rate equation for the reaction and its overall order, using your answer from (b)(i).

Rate equation:

Overall order:
19M.2.hl.TZ2.2c(i):
Deduce how the rate of reaction at t = 2 would compare to the initial rate.
19M.2.hl.TZ2.2c(ii):
It has been suggested that the reaction occurs as a two-step process:

Step 1: N₂O (g) → N₂ (g) + O (g)

Step 2: N₂O (g) + O (g) → N₂ (g) + O₂ (g)

Explain how this could support the observed rate expression.
19M.2.hl.TZ2.c(i):
Deduce how the rate of reaction at t = 2 would compare to the initial rate.
19M.2.hl.TZ2.c(ii):
It has been suggested that the reaction occurs as a two-step process:

Step 1: N₂O (g) → N₂ (g) + O (g)

Step 2: N₂O (g) + O (g) → N₂ (g) + O₂ (g)

Explain how this could support the observed rate expression.
19M.1.hl.TZ1.20: Which graph is obtained from a first order reaction?
19M.1.hl.TZ1.21: Which is correct for the reaction mechanism shown?
19M.1.hl.TZ2.20:
Which statement is correct about a catalyst?

A. It decreases the activation energy of the forward reaction but not the reverse.

B. It increases the proportion of products to reactants in an equilibrium.

C. It decreases the enthalpy change of the reaction.

D. It changes the mechanism of the reaction.
19M.1.hl.TZ2.21:
What is the order with respect to each reactant?

2NO (g) + Cl₂ (g) → 2NOCl (g)
19N.2.hl.TZ0.1e(i): Identify the steps which absorb ultraviolet light.
19N.2.hl.TZ0.e(i): Identify the steps which absorb ultraviolet light.
19N.2.hl.TZ0.3b(i):
Determine the rate expression from the results, explaining your method.
19N.2.hl.TZ0.b(i):
Determine the rate expression from the results, explaining your method.
19N.1.hl.TZ0.21: Which is correct?
20N.1.hl.TZ0.20:
What are the units of the rate constant, $k$ , if the rate equation is $Rate = k [A] {[B]}^{2}$ ?

A.   $mol {dm}^{- 3} s^{- 1}$

B.   ${dm}^{3} {mol}^{- 1} s^{- 1}$

C.   ${dm}^{6} {mol}^{- 2} s^{- 1}$

D.   ${dm}^{9} {mol}^{- 3} s^{- 1}$
20N.1.hl.TZ0.21:
Which graph represents the relationship between the rate constant, $k$ , and temperature, $T$ , in kelvin?
21M.1.hl.TZ1.20:
A reaction proceeds by the following mechanism:

step 1: $A + A \to B$
step 2: $B + C \to D$

Which rate equation is consistent with this mechanism?

A. Rate = k[B]²[C]

B. Rate = k[A]²[B][C]

C. Rate = k[A]²

D. Rate = k[A][C]
21M.1.hl.TZ1.21: Which graphs show a first order reaction? A. V and X B. V and Y C. W and X D. W and Y
21M.1.hl.TZ2.20: Which graph represents a second order reaction with respect to X? X → Y
21M.2.hl.TZ1.6b(iii):
Write the rate expression for this reaction.
21M.2.hl.TZ1.6b(iv):
Calculate the value of the rate constant, k, giving its units.
21M.2.hl.TZ1.b(iii):
Write the rate expression for this reaction.
21M.2.hl.TZ1.b(iv):
Calculate the value of the rate constant, k, giving its units.
21M.2.hl.TZ1.7c:
Explain, using equations, how the presence of ${CCl}_{2} F_{2}$ results in a chain reaction that decreases the concentration of ozone in the stratosphere.
21M.2.hl.TZ1.c:
Explain, using equations, how the presence of ${CCl}_{2} F_{2}$ results in a chain reaction that decreases the concentration of ozone in the stratosphere.
21M.2.hl.TZ2.6a:
Determine the rate expression for the reaction.
21M.2.hl.TZ2.6b:
Determine the value and unit of the rate constant using the rate expression in (a).
21M.2.hl.TZ2.a:
Determine the rate expression for the reaction.
21M.2.hl.TZ2.b:
Determine the value and unit of the rate constant using the rate expression in (a).
21N.1.hl.TZ0.20: Which graph shows a first order reaction?
21N.1.hl.TZ0.21:
The rate equation for a reaction is:

rate = k[A][B]

Which mechanism is consistent with this rate equation?

A. 2A $⇌$ I Fast
I + B → P Slow

B. A + B $⇌$ I Fast
I + A → P Slow

C. A → I Slow
I + B → P Fast

D. B $⇌$ I Fast
I + A → P Slow
21N.2.hl.TZ0.10c(i):
Deduce the rate expression for this reaction.
21N.2.hl.TZ0.10c(ii): Deduce the units of the rate constant.
21N.2.hl.TZ0.10c(iii):
Determine the initial rate of reaction in experiment 4.
21N.2.hl.TZ0.10d: Deduce, with a reason, the mechanism of the reaction between 2-chloropentane and sodium hydroxide.
21N.2.hl.TZ0.c(i):
Deduce the rate expression for this reaction.
21N.2.hl.TZ0.c(ii): Deduce the units of the rate constant.
21N.2.hl.TZ0.c(iii):
Determine the initial rate of reaction in experiment 4.
21N.2.hl.TZ0.d: Deduce, with a reason, the mechanism of the reaction between 2-chloropentane and sodium hydroxide.
22M.1.hl.TZ1.20: The table shows data for the hydrolysis of a halogenoalkane, RCl. Which statements are...
22M.1.hl.TZ1.21:
What is the activation energy according to the following plot of the linear form of the Arrhenius equation?

Arrhenius equation: $k = A e^{\frac{- E a}{R T}}$ .

A. $E_{a} = \frac{2 \times 8.31}{0.06}$

B. $E_{a} = \frac{- 2 \times 8.31}{0.06}$

C. $E_{a} = e^{\frac{2 \times 8.31}{0.06}}$

D. $E_{a} = e^{\frac{- 2 \times 8.31}{0.06}}$
22M.1.hl.TZ2.19:
What is correct about the rate of disappearance of NO?

2NO (g) + 2H₂(g) → N₂(g) + 2H₂O (g)

rate = k[H₂][NO]²

A. It equals half the rate of disappearance of H₂.

B. It equals the rate of disappearance of H₂.

C. It equals twice the rate of disappearance of H₂.

D. It equals four times the rate of disappearance of H₂.
22M.1.hl.TZ2.20: Which energy profile diagram represents an exothermic SN1 reaction?
22M.2.hl.TZ1.2c(i):
Use the graph to deduce the dependence of the reaction rate on the amount of Mg.
22M.2.hl.TZ1.2c(ii):
The reaction is first order with respect to HCl. Calculate the time taken, in seconds (s), for half of the Mg to dissolve when [HCl] = 0.5 mol dm^–3.
22M.2.hl.TZ1.c(i):
Use the graph to deduce the dependence of the reaction rate on the amount of Mg.
22M.2.hl.TZ1.c(ii):
The reaction is first order with respect to HCl. Calculate the time taken, in seconds (s), for half of the Mg to dissolve when [HCl] = 0.5 mol dm^–3.
22M.2.hl.TZ2.4a(i):
Deduce the order of reaction with respect to hydrogen.
22M.2.hl.TZ2.4a(ii):
Deduce the rate expression for the reaction.
22M.2.hl.TZ2.4a(iii):
Calculate the value of the rate constant stating its units.
22M.2.hl.TZ2.a(i):
Deduce the order of reaction with respect to hydrogen.
22M.2.hl.TZ2.a(ii):
Deduce the rate expression for the reaction.
22M.2.hl.TZ2.a(iii):
Calculate the value of the rate constant stating its units.
22N.1.hl.TZ0.20:
Data is given for the reaction 2X₂ (g) + Y₂ (g) → 2X₂Y (g).

What rate equation can be inferred from the data?

A. Rate = k [X₂] [Y₂]

B. Rate = k [X₂]² [Y₂]

C. Rate = k [X₂]² [Y₂]⁰

D. Rate = k [X₂]² [Y₂]²
22N.1.hl.TZ0.21:
The activation energy of a reaction can be obtained from the rate constant, k, and the absolute temperature, $T$ . Which graph of these quantities produces a straight line?

A. k against $T$

B. k against $\frac{1}{T}$

C. ln k against $T$

D. ln k against $\frac{1}{T}$
22N.2.hl.TZ0.6a:
This reaction could proceed through either S_N1 or S_N2 mechanisms depending on the reaction conditions. Sketch a graph of the rate versus nucleophile concentration, [CN⁻], for each of the mechanisms.
22N.2.hl.TZ0.a:
This reaction could proceed through either S_N1 or S_N2 mechanisms depending on the reaction conditions. Sketch a graph of the rate versus nucleophile concentration, [CN⁻], for each of the mechanisms.
17N.1.hl.TZ0.21:
The rate expression for the reaction X (g) + 2Y (g) → 3Z (g) is

rate = k[X]⁰ [Y]²

By which factor will the rate of reaction increase when the concentrations of X and Y are both increased by a factor of 3?

A. 6

B. 9

C. 18

D. 27
17N.1.hl.TZ0.22: Which pair of statements explains the increase in rate of reaction when the temperature...
17N.2.hl.TZ0.2e.i: Deduce the order of reaction with respect to Cl2 and NO.
17N.2.hl.TZ0.2e.ii:
State the rate expression for the reaction.
17N.2.hl.TZ0.2e.iii: Calculate the value of the rate constant at 263 K.
17N.2.hl.TZ0.e.i: Deduce the order of reaction with respect to Cl2 and NO.
17N.2.hl.TZ0.e.ii:
State the rate expression for the reaction.
17N.2.hl.TZ0.e.iii: Calculate the value of the rate constant at 263 K.
18M.1.hl.TZ1.19: What are correct labels for the Maxwell−Boltzmann energy distribution curves?
18M.1.hl.TZ1.20: The reaction between NO2 and F2 gives the following rate data at a certain temperature. What...
18M.2.hl.TZ1.4b.iv:
Deduce the rate expression for the reaction.
18M.2.hl.TZ1.4b.v:
Calculate the rate constant of the reaction, stating its units.
18M.2.hl.TZ1.b.iv:
Deduce the rate expression for the reaction.
18M.2.hl.TZ1.b.v:
Calculate the rate constant of the reaction, stating its units.
18M.1.hl.TZ2.20: When X reacts with Y to give Z, the following graph is plotted. What can be deduced from the...
18M.1.hl.TZ2.21: Which statement is correct? A. The value of the rate constant, k, is independent of...

23M.1.HL.TZ1.14:

What is the enthalpy change for the following reaction?

CH₄ (g) + H₂O (g) → CO (g) + 3H₂ (g)

Reaction	ΔH^⦵
2C_(graphite) + O₂ (g) → 2CO (g)	−222 kJ mol⁻¹
C_(graphite) + 2H₂ (g) → CH₄ (g)	−74 kJ mol⁻¹
2H2 (g) + O₂ (g) → 2H₂O (g)	−484 kJ mol⁻¹

A. −74 − 242 + 111

B. +74 + 242 − 111

C. −74 − 484 − 222

D. +74 + 484 − 222

18N.1.hl.TZ0.20: Compounds X and Y were mixed and the time taken for a colour to appear was recorded at various...
18N.1.hl.TZ0.21:
The rate expression for the reaction is: rate = k [NO]²[O₂].

2NO (g) + O₂ (g) → 2NO₂ (g)

Which mechanism is not consistent with this rate expression?
18N.2.hl.TZ0.10a: Classify substances B and D as reactant, product, catalyst, or intermediate, based on the...
18N.2.hl.TZ0.10b:
Deduce the rate expression.
18N.2.hl.TZ0.10c: Calculate the initial rate of reaction for experiment 2, if measured under the same conditions.
18N.2.hl.TZ0.a: Classify substances B and D as reactant, product, catalyst, or intermediate, based on the...
18N.2.hl.TZ0.b:
Deduce the rate expression.
18N.2.hl.TZ0.c: Calculate the initial rate of reaction for experiment 2, if measured under the same conditions.

16.2 Activation energy