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IB Chemistry HL 1.1 Measuring Enthalpy Changes Questions

Practise IB Chemistry HL 4.1 with evidence-led questions on reactivity, reaction types, acids, bases and chemical change.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Distinguish endothermic and exothermic processes using energy transfer and the sign of enthalpy change.
  • Use calorimetry data to calculate an enthalpy change with consistent units and appropriate significant figures.
  • Relate chemical stability to relative energy and interpret reaction evidence using an energy model.
  • Define and use standard enthalpy changes for chemical reactions under stated conditions.

Covered syllabus points

1.1.1—Energy transfer1.1.2—Endothermic vs. exothermic1.1.3—Stability and energy1.1.4—Standard enthalpy change (ΔH⦵)

Learn this topic

Study 1.1 Measuring enthalpy changes conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

Question 1

[Maximum number: 1]

The increased concentration of carbon dioxide in the atmosphere is thought to result from the increased combustion of fossil fuels such as petroleum.

Outline why the energy available from an engine will be less than these theoretical values.

Question 2

[Maximum number: 1]

Two groups of students (Group A and Group B) carried out a project* on the chemistry of some group 7 elements (the halogens) and their compounds.

In the first part of the project, the two groups had a sample of iodine monochloride (a corrosive brown liquid) prepared for them by their teacher using the following reaction.

I2( s)+Cl2( g)→2ICl(l)\mathrm{I}_{2}(\mathrm{~s})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{ICl}(\mathrm{l})

The following data were recorded.

Table for Question 2 — IB Chemistry HL

Using a digital thermometer, the students discovered that the reaction was exothermic. State the sign of the enthalpy change of the reaction, ΔH\Delta H.

Question 3

[Maximum number: 3]

Phenylethene (styrene) is produced from ethylbenzene in a gas-phase equilibrium.

Figure for Question 3 — IB Chemistry HL

The forward reaction is endothermic, uses iron(III) oxide as a catalyst, and takes place at 900 K .

Sketch the energy profile for the reaction, both with and without the catalyst, labelling ΔH\Delta H and the activation energies.

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