Chapter 6, Problem 6.44QP

Interpretation Introduction

Interpretation: The determination of ${\text{ΔH}}_{\text{f}}\text{°}$ of the compound by measuring the heat of combustion has to be explained.

Concept Introduction:

The enthalpy change for given set of reactants to the given set of products is the same, whether the process takes place in single or sequence of steps.  This is called as Hess’s law.

Enthalpy is generally calculated from the standard enthalpy of formation.

${\text{ΔH°}}_{\text{reaction}}\text{=}\sum {\text{n}}_{\text{p}}{\text{ΔH}}^{\text{°}}{}_{\text{f}}\text{(products)-}\sum {\text{n}}_{\text{p}}{\text{ΔH}}^{\text{°}}\text{(reactants)}$

In thermochemistry, it is used to determine the lattice energy of ionic compounds.