Chapter 18, Problem 62E

Interpretation Introduction

Introduction:

• The value of enthalpy of reaction is calculated using the standard enthalpy of formations of the compounds. Standard enthalpy of formation of elements is zero.

The standard enthalpy of the reaction is given by:

$\Delta H_{rxn}^{\circ }={{\displaystyle \sum n}}_p\Delta H_f^{\circ }\left(products\right)-{{\displaystyle \sum n}}_r\Delta H_f^{\circ }\left(\text{reactants}\right)$

Here, $n_p$is the stoichiometric coefficients of products and $n_r$ is the stoichiometric coefficients of reactants.

• The standard entropy of the reaction is given by:

$\Delta S_{rxn}^{\circ }={{\displaystyle \sum n}}_p\Delta S^{°}\left(products\right)-{{\displaystyle \sum n}}_r\Delta S^{°}\left(\text{reactants}\right)$

Here, $n_p$is the stoichiometric coefficients of products and $n_r$ is the stoichiometric coefficients of reactants.

y The value of Gibbs free energy change in the reaction is calculated using the standard enthalpy and entropy of the reaction.

$\Delta G_{rxn}^{\circ }=\Delta H_{rxn}^{\circ }-T\Delta S_{rxn}^{\circ }$