Chapter 15, Problem 15.158MP

Interpretation Introduction

(a)

Interpretation:

The value of ${\text{K}}_{\text{c}}$ at $\text{T = 400K}$ needs to be determined.

Concept introduction:

At the equilibrium condition, the number is used to express the relationship between reactants and products at the given temperature in a reversible chemical heat reaction, which is equilibrium constant.

For a reversible chemical reaction:

$\text{aA + bB }\to \text{cC + dD}$

The equilibrium constant $\text{K}$ is given by the following expression:

$\text{K = }{\left[\text{C}\right]}^{\text{c}}\text{·}{\left[\text{D}\right]}^{\text{d}}\text{/}{\left[\text{A}\right]}^{\text{a}}\text{·}{\left[\text{B}\right]}^{\text{b}}$

Where,

Equilibrium concentration of $\text{A}$ : $\left[\text{A}\right]$

Equilibrium concentration of $\text{B}$ : $\left[\text{B}\right]$

Equilibrium concentration of $\text{C}$ : $\left[\text{C}\right]$

Equilibrium concentration of $\text{D}$ : $\left[\text{D}\right]$

Interpretation Introduction

(b)

Interpretation:

The heat absorbed by ${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}$ for decomposition needs to be determined.

Concept introduction:

For a reversible chemical reaction:

$\text{aA + bB }\to \text{cC + dD}$

The change in enthalpy of reaction can be calculated as follows:

$\Delta H_{rxn}=c\Delta H\left(C\right)+d\Delta H\left(D\right)-a\Delta H\left(A\right)-b\Delta H\left(B\right)$