IBDP Official Exam Material
FREE Past Paper Questions by Topic
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Topic 6: Chemical Kinetics
For both SL and HL students
1. [1 mark]
What initial rate of reaction can be determined from the graph?
A. 0.1 mol dm−3 s−1
B. 0.2 mol dm−3 s−1
C. 1.0 mol dm−3 s−1
D. 1.6 mol dm−3 s−1
2. [1 mark]
Which changes would increase the rate of an exothermic reaction?
3. [1 mark]
A sample of calcium carbonate reacts with excess hydrochloric acid in a beaker. The solid line shows how the mass of the beaker changes with time.
Which dashed line represents the results obtained when the acid concentration is doubled?
4. [1 mark]
A student was investigating rates of reaction. In which of the following cases would a colorimeter show a change in absorbance?
A. KBr (aq) + Cl2 (aq)
B. Cu (s) + Na2SO4 (aq)
C. HCl (aq) + NaOH (aq)
D. (CH3)3COH (aq) + K2Cr2O7 (aq)
5. [1 mark]
Annotate the Maxwell–Boltzmann distribution curve showing the activation energies, Ea, for the catalysed and uncatalysed reactions.
6. [1 mark]
Explain, referring to the Maxwell–Boltzmann distribution curve, the effect of a catalyst on a chemical reaction.
7. [2 marks]
Sodium thiosulfate reacts with hydrochloric acid as shown:
Na2S2O3 (aq) + 2HCl (aq) → S (s) + SO2 (aq) + 2NaCl (aq) + H2O (l)
The precipitate of sulfur makes the mixture cloudy, so a mark underneath the reaction mixture becomes invisible with time.
Suggest two variables, other than concentration, that should be controlled when comparing relative rates at different temperatures.
10a. [2 marks]
Sulfur trioxide is produced from sulfur dioxide.
2SO2 (g) + O2 (g) ⇌ 2SO3 (g) ΔH = −196 kJ mol−1
Outline, giving a reason, the effect of a catalyst on a reaction.
10b. [3 marks]
The reaction between sulfur dioxide and oxygen can be carried out at different temperatures.
On the axes, sketch Maxwell–Boltzmann energy distribution curves for the reacting species at two temperatures T1 and T2, where T2 > T1.
11. [1 mark]
Which combination has the greatest rate of reaction at room temperature?
12. [1 mark]
Curve 1 shows the mass change when marble chips are added to excess hydrochloric acid in an open beaker.
Which changes would produce curve 2?
A. Powdering the marble chips and heating
B. Powdering the marble chips and doubling their mass
C. Doubling the volume of acid and heating
D. Doubling the acid concentration and powdering the marble chips
13. [1 mark]
The graph shows the Maxwell–Boltzmann energy distribution curve for a given gas at a certain temperature.
How would the curve change if the temperature of the gas decreases while the other conditions remain constant?
A. The maximum would be lower and to the left of M.
B. The maximum would be lower and to the right of M.
C. The maximum would be higher and to the left of M.
D. The maximum would be higher and to the right of M.
14. [2 marks]
Hydrogen peroxide can react with methane and oxygen to form methanol. This reaction can occur below 50°C if a gold nanoparticle catalyst is used.
The diagram shows the Maxwell-Boltzmann curve for the uncatalyzed reaction.
Draw a distribution curve at a lower temperature (T2) and show on the diagram how the addition of a catalyst enables the reaction to take place more rapidly than at T1.
15. [1 mark]
Which change causes the greatest increase in the initial rate of reaction between nitric acid and magnesium?
2HNO3 (aq) + Mg (s) → Mg(NO3)2 (aq) + H2 (g)
If you need the markscheme, including the examiners' reports for each question, and more exam and teaching materials on this topic, contact me through the contact page