Thermochemistry Fundamentals
What You Will Learn: Thermochemistry Fundamentals · Enthalpy and Heat Changes · Standard Enthalpy Changes and Hess’s Law Preparation
IB Chemistry topic guide
Reactivity 1: What Drives Reactions?
Reactivity 1: What Drives Reactions? is a core part of IB Chemistry. This guide connects the syllabus ideas behind Thermochemistry Fundamentals, Calorimetry, Energy Cycles, Bonding and Enthalpy, Entropy and Spontaneity, shows how they appear in worked problems, and points you to the formulas and full lessons needed for exam revision.
What you will learn
Reactivity 1: What Drives Reactions? syllabus outline
The units below follow the structure used in the full Study to Learn course. Use the outline to identify exactly which idea needs attention, then work through the public example before continuing to the complete lesson path.
Calorimetry
What You Will Learn: Calorimetry · The Calorimetry Calculation · Sources of Error and Improving Accuracy
Energy Cycles
What You Will Learn: Energy Cycles · Hess’s Law · Born–Haber Cycles
Bonding and Enthalpy
What You Will Learn: Bonding and Enthalpy · Bond Enthalpies · Bond Length, Bond Order, and Why Averages Vary
Entropy and Spontaneity
What You Will Learn: Entropy and Spontaneity · Entropy and Gibbs Free Energy · Predicting Entropy Changes and Finding the Switching Temperature
Free worked preview
What You Will Learn: Thermochemistry Fundamentals
This complete preview comes from the Thermochemistry Fundamentals unit. It introduces the core language, shows the method in context, and gives you a real example of the lesson quality before you create an account.
What You Will Learn: Thermochemistry Fundamentals
Section D asks what drives chemical reactions, starting with energy. This opening topic introduces enthalpy, the key thermodynamic quantity for measuring heat change in a reaction at constant pressure. The first lesson defines exothermic and endothermic reactions and how to read enthalpy level diagrams. The second lesson introduces the specific standard enthalpy changes (formation, combustion) that are tabulated in the data booklet, setting up Hess's Law calculations in Topic D2, which combine these tabulated values to find enthalpy changes that cannot be measured directly.
What You'll Cover
- Exothermic and endothermic reactions, enthalpy level diagrams, and the sign convention for ΔH.
- Standard enthalpy changes of formation and combustion, and how these tabulated values become the building blocks for Hess's Law calculations.
By the end of this topic you will understand what enthalpy measures and be ready to combine standard values using Hess's Law.
Reviewed by the Study to Learn editorial team · Updated 2026-08-04