Chemistry A-Level
Hess's law rearrangement
What Hess's law rearrangement means in Chemistry A-Level, as defined for OCR.
Definition of Hess's law rearrangement
Check what you remember
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Reference: OCR
Setting the enthalpy of formation equal to the sum of the steps on the indirect route, then rearranging for the unknown term before substituting values.
Topics that use Hess's law rearrangement
- Lattice enthalpy (OCR A-Level)
Related terms
- Born–Haber cycle
- Effect of ionic charge and radius on lattice enthalpy
- Electron affinity
- Enthalpy change of hydration
- Enthalpy change of solution
- Enthalpy of atomisation
- enthalpy of formation
- Enthalpy sign and exothermic formation
Using Hess's law rearrangement in the exam
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