IB Chemistry HL 1.2.2 Hess's law
IB Chemistry HL 1.2.2 Hess's law
Use Hess's law to reverse, multiply and add equations correctly, then extract a missing ΔH or choose the valid expression from an enthalpy cycle.
How this is tested
- calculate ΔH by reversing and scaling equations before adding their enthalpy values
- deduce a missing ΔH from an energy cycle with correct sign handling
- select the correct algebraic expression for reactions such as O2 to O3 or propyne to propene