Thermodynamics: Standard Enthalpy of Formation

It's time for Prof Al, from the chemistry department at AUT, to tell you about standard enthalpies of formation, and how they can be used to calculate standard enthalpies of reaction using Hess's Law in disguise.

The worked problem: Calculate the enthalpy change for the reaction

NH₃(g) + HCl(g) → NH₄Cl(s)

given the following standard enthalpy of formation data

ΔfH(NH₃,g) = -46.19 kJ mol⁻¹ 

ΔfH(HCl,g) = -92.30 kJ mol⁻¹ 

ΔfH(NH₄Cl,s) = -315.4 kJ mol⁻¹

Видео Thermodynamics: Standard Enthalpy of Formation канала Auckland University of Technology