CourseCourseConceptConceptDocsDocuments

IB Chemistry HL 1.2.3 Hl Standard Enthalpy Changes Questions

Use real HL exam questions to write defining formation or combustion equations, calculate ΔH from tabulated values and scale energy changes by stoichiometry.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Write or identify the defining standard enthalpy of formation or combustion equation for exactly one mole, with elements/compound in their standard states.
  • Calculate a standard reaction enthalpy from standard enthalpies of formation using the signed products-minus-reactants sum and correct stoichiometric coefficients.
  • Use standard molar enthalpy values and stoichiometry to determine energy released or absorbed for the specified amount or complete combustion reaction, reporting units and sign convention.

Learn this topic

Study 1.2.3 (HL)—Standard enthalpy changes conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry HL 1.2.3 Hl Standard Enthalpy Changes Questions question 1

[Maximum number: 1]

Phosphoryl chloride, POCl3\mathrm{POCl}_{3}, is a dehydrating agent.

POCl3( g)\quad \mathrm{POCl}_{3}(\mathrm{~g}) decomposes according to the following equation.

2POCl3( g)→2PCl3( g)+O2( g)2 \mathrm{POCl}_{3}(\mathrm{~g}) \rightarrow 2 \mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})

Define the term standard enthalpy change of formation, ΔHf⊖\Delta H_{\mathrm{f}}{ }^{\ominus}.

All question bank results loaded