Chapter 4, Problem 4.11CP

Interpretation Introduction

Interpretation:

The reason for the reaction enthalpy associated with the formation of NO₂ from NO and O₂ irrespective of how the temperature is controlled needs to be provided.

Concept Introduction:

Enthalpy change of a reaction is the amount of heat absorbed or evolved during the reaction which takes place at constant pressure conditions The standard enthalpy change for a reaction ${\text{ΔH}}_{\text{R}}^{\text{0}}$ measured at 298 K and 1 atm is given in terms of the difference in the standard enthalpy of formation of the products and that of reactants.

i.e. ${\text{ΔH}}_{\text{R}}^{\text{0}}\text{ = }{\displaystyle \sum {\text{n}}_{\text{p}}{\text{ΔH}}_{\text{f}}^{\text{0}}}\text{(products) - }{\displaystyle \sum {\text{n}}_{\text{r}}{\text{ΔH}}_{\text{f}}^{\text{0}}}\text{(reactants) ------(1)}$

Here, np and nr are the numbers of moles of the products and reactants