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Topic 16: Chemical Kinetics
For HL students only
1. [1 mark]
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]
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
2. [1 mark]
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 1T
C. ln k against T
D. ln k against 1T
3. [1 mark]
The table shows data for the hydrolysis of a halogenoalkane, RCl.
Which statements are correct?
I. The reaction is first order with respect to RCl.
II. The reaction is second order overall.
III. The reaction proceeds by an SN2 mechanism.
II. The reaction is second order overall.
III. The reaction proceeds by an SN2 mechanism.
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
4. [1 mark]
What is the activation energy according to the following plot of the linear form of the Arrhenius equation?
5. [1 mark]
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.
6. [1 mark]
Which factor influences the value of the pre-exponential factor, A, in the Arrhenius equation, k=Ae-Ea/RT?
A. Nature of reactants
B. Temperature of reaction
C. Activation energy of reaction
D. Overall order of the reaction
7a. [1 mark]
Hydrogen and iodine react to form hydrogen iodide.
H2 (g) + I2 (g) ⇌ 2HI (g)
The following experimental data was obtained.
Deduce the order of reaction with respect to hydrogen.
7b. [1 mark]
Deduce the rate expression for the reaction.
7c. [2 marks]
Calculate the value of the rate constant stating its units.
7d. [1 mark]
State two conditions necessary for a successful collision between reactants.
7e. [1 mark]
State the equilibrium constant expression, Kc, for this reaction.
8. [1 mark]
What are the units of the rate constant, k, if the rate equation is Rate=kAB2?
A. mol dm-3 s-1
B. dm3 mol-1 s-1
C. dm6 mol-2 s-1
D. dm9 mol-3 s-1
9. [1 mark]
Which graph represents the relationship between the rate constant, k, and temperature, T, in kelvin?
10. [1 mark]
Which is correct?
11. [1 mark]
What is the intercept on the y-axis when a graph of lnk is plotted against 1T on the x-axis?
lnk=-EaRT+lnA
A. lnA
B. -EaR
C. -REa
D. Ea
12. [1 mark]
Which graph is obtained from a first order reaction?
13. [1 mark]
What are the units for the rate constant, k, in the expression?
Rate = k [X]2[Y]
A. mol2 dm−6 s−1
B. mol−1 dm3 s−1
C. mol dm−3 s−1
D. mol−2 dm6 s−1
14. [1 mark]
Which is the first step in the CFC-catalysed destruction of ozone in UV light?
A. CCl2F2 → CClF2+ + Cl–
B. CCl2F2 → •CClF2 + Cl•
C. CCl2F2 → CCl2F+ + F–
D. CCl2F2 → •CCl2F + F•
15. [1 mark]
Which is true of an Arrhenius plot of lnk (y-axis) against 1T?
A. The graph goes through the origin.
B. The activation energy can be determined from the gradient.
C. The intercept on the x-axis is the activation energy.
D. The intercept on the y-axis is the frequency factor, A.
16. [1 mark]
Which is correct about reaction mechanisms?
A. A species that is zero order does not take part in the reaction.
B. A catalyst does not take part in the reaction.
C. Reactants in a fast step before the slow step are included in the rate expression.
D. Reactants in a fast step after the slow step are included in the rate expression.
17. [1 mark]
Which statement describes the characteristics of a transition state relative to the potential energy of the reactants and products?
A. It is an unstable species with lower potential energy.
B. It is an unstable species with higher potential energy.
C. It is a stable species with lower potential energy.
D. It is a stable species with higher potential energy.
18. [3 marks]
Sodium thiosulfate solution reacts with dilute hydrochloric acid to form a precipitate of sulfur at room temperature.
Na2S2O3 (aq) + 2HCl (aq) → S (s) + SO2 (g) + 2NaCl (aq) + X
(i) Using the graph, explain the order of reaction with respect to sodium thiosulfate.
(ii) In a different experiment, this reaction was found to be first order with respect to hydrochloric acid. Deduce the overall rate expression for the reaction.
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