R2.2 How fast? The rate of chemical change questions for IB Chemistry

169 questions on How fast? The rate of chemical change, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

IB Chemistry
Part of R2 How much, how fast and how far?
SL and HL

Questions by paper and level

SL and HL questions are for students at either level. HL only questions cover what only HL students study.

Paper	SL and HL	HL only	All
Paper 1A	34	33	67
Paper 1B	19	14	33
Paper 2	33	36	69
Every paper	86	83	169

Counted on 10 November 2026

Questions to try

Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · CHEM-00330Paper 1A · 1 mark

Why is a high activation energy a useful property of a fuel?

A
It makes the combustion reaction more exothermic.
B
The fuel does not ignite at room temperature until energy is supplied, for example by a spark.
C
It increases the energy density of the fuel.
D
It ensures that the fuel undergoes complete combustion.

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Question 2 · CHEM-00987Paper 1B · 6 marks

A student prepared solutions of sodium thiosulfate of different concentrations for a rate experiment by diluting a 0.200 mol dm⁻³ stock solution with distilled water. The volumes were measured with a 50 cm³ measuring cylinder (± 0.5 cm³).

Mixture	1	2	3	4	5
Volume of stock solution / cm³	50.0	40.0	30.0	20.0	10.0
Volume of water / cm³	0.0	10.0	20.0	30.0	40.0
[Na₂S₂O₃] / mol dm⁻³	0.200	0.160		0.0800	0.0400

(a)
Calculate the concentration of sodium thiosulfate in mixture 3.
1 mark
(b)
Calculate the amount, in mol, of sodium thiosulfate in mixture 4.
1 mark
(c)
The stock solution was made from sodium thiosulfate pentahydrate, Na₂S₂O₃·5H₂O. Calculate the mass needed to make 500.0 cm³ of the stock solution.
2 marks
(d)
Calculate the percentage uncertainty in the volume of stock solution used for mixture 5.
1 mark
(e)
Suggest a change to the apparatus that would reduce the uncertainty in (d).
1 mark

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Question 3 · CHEM-00759Paper 2 · HL only · 8 marks

Iron is a transition element. Finely divided iron is the catalyst in the Haber process for the manufacture of ammonia.

(a)
State the condensed electron configuration of an iron atom.
1 mark
(b)
Deduce the condensed electron configurations of Fe²⁺ and Fe³⁺.
2 marks
(c)
Explain why iron can form ions with different charges.
2 marks
(d)
The melting point of iron is 1538 °C and that of calcium is 842 °C. Explain this difference.
2 marks
(e)
State one characteristic property of transition elements, other than catalytic activity, variable oxidation state and high melting point, that is shown by iron.
1 mark

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Question 4 · CHEM-00366Paper 1A · 1 mark

The table gives the potential energy of the reactants, the highest point on the reaction pathway and the products for a reaction.

Point on the energy profile	Potential energy / kJ mol⁻¹
Reactants	150
Highest point (transition state)	230
Products	60

What is the enthalpy change, ΔH, for the reaction, in kJ mol⁻¹?

A
−170
B
−90
C
+80
D
+90

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Question 5 · CHEM-01061Paper 1B · HL only · 10 marks

A student compared metal oxides as catalysts for the decomposition of hydrogen peroxide. 0.50 g of a powdered oxide was added to 25.0 cm³ of 0.50 mol dm⁻³ hydrogen peroxide in a conical flask connected to a gas syringe. The volume of oxygen collected after 60 s was recorded.

Oxide	Volume of O₂ after 60 s / cm³ ± 1 cm³
none	0
manganese(IV) oxide, MnO₂	62
lead(IV) oxide, PbO₂	47
copper(II) oxide, CuO	9
iron(III) oxide, Fe₂O₃	4
zinc oxide, ZnO	1

(a)
Write the equation for the decomposition of hydrogen peroxide.
1 mark
(b)
State two variables, other than the mass of oxide, that should be controlled.
2 marks
(c)
Calculate the mean rate of oxygen production, in cm³ s⁻¹, with manganese(IV) oxide over the first 60 s.
1 mark
(d)
Calculate the maximum volume of oxygen that could be produced, in cm³. Assume the molar volume of a gas under the conditions of the experiment is 24.8 dm³ mol⁻¹.
2 marks
(e)
The student concluded that "only oxides of transition elements are effective catalysts for this reaction". Evaluate this conclusion using the data.
2 marks
(f)
Outline how the student could show that manganese(IV) oxide is not used up in the reaction.
1 mark
(g)
Deduce the oxidation state of manganese in MnO₂.
1 mark

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Question 6 · CHEM-00761Paper 2 · HL only · 9 marks

Successive ionization energies of calcium and manganese are shown.

Ionization energy / kJ mol⁻¹	1st	2nd	3rd	4th	5th
Ca	590	1145	4912	6491	8153
Mn	717	1509	3248	4940	6990

(a)
Deduce the condensed electron configurations of a manganese atom and of the Mn²⁺ ion.
2 marks
(b)
Explain, using the data, why calcium shows only the +2 oxidation state in its compounds while manganese shows several oxidation states.
2 marks
(c)
Deduce the oxidation state of manganese in $M n O_{2}$ , $K_{2} M n O_{4}$ and $K M n O_{4}$ .
3 marks
(d)
Manganese(IV) oxide catalyses the decomposition of hydrogen peroxide. Write the equation for this decomposition.
1 mark
(e)
Suggest one reason why transition elements and their compounds are often effective catalysts.
1 mark

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