CourseCourseConceptConceptDocsDocuments

IB Chemistry HL 1.4.1 Hl Entropy S Questions

Use real HL exam questions to calculate ΔS from standard entropy data, predict its sign from particle dispersal and compare entropy ordering.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Calculate standard entropy change as ΣS°(products) − ΣS°(reactants), applying stoichiometric coefficients and reporting J K⁻¹ mol⁻¹ units.
  • Predict the sign or direction of ΔS from changes of state, gas-particle count and the dispersal or ordering of matter and energy.
  • Interpret standard entropy data to compare entropy values or disorder changes, using Sgas > Sliquid > Ssolid and particle-distribution evidence.

Learn this topic

Study 1.4.1 (HL)—Entropy (S) conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry HL 1.4.1 Hl Entropy S Questions question 1

[Maximum number: 1]

Nitrous acid, HNO2\mathrm{HNO}_{2}, is a weak acid which can be used to make acidic buffers.

The overall reaction for the synthesis of ethyl ethanoate from ethane is:

2C2H6( g)+Cl2( g)+32O2( g)→C4H8O2( g)+2HCl( g)+H2O( g)2 \mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g})+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}(\mathrm{~g})+2 \mathrm{HCl}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{~g})

Calculate the standard entropy change, ΔSθr\Delta S^{\theta}{ }_{r}, in JK−1 mol−1\mathrm{JK}^{-1} \mathrm{~mol}^{-1}, for this reaction. Use section 13 of the data booklet and Sθ\mathrm{S}^{\theta} of ethyl ethanoate =259JK−1 mol−1=259 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}.

All question bank results loaded