IB Chemistry - Energetics

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Hess' law is the fundamental basis behind all thermodynamic data and measurement. It emerges directly from the law of conservation of energy. The simplest statement of the law is:

"The energy change between two different states is independent of the route taken between them".

Syllabus reference

Reactivity 1.2.2 - Hess’s law states that the enthalpy change for a reaction is independent of the pathway between the initial and final states.

  • Apply Hess’s law to calculate enthalpy changes in multistep reactions.


Tools and links

In Chapter 4.3