Applications of Hess’s law

Hess’s law.

Students should be able to:

• use Hess’s law to perform calculations, including calculation of enthalpy changes for reactions from enthalpies of combustion or from enthalpies of formation.

MS 2.4

Students carry out Hess's law calculations.

AT a and k

PS 2.4, 3.2 and 4.1

Students could be asked to find ∆H for a reaction using Hess’s law and calorimetry, then present data in appropriate ways. Examples of reactions could include:

• thermal decomposition of NaHCO₃

• hydration of MgSO₄

• hydration of CuSO₄