Chapter 18.4, Problem 2CYU

(a)

Interpretation Introduction

Interpretation:

The standard entropy changes for the following given ${\text{NH}}_{\text{4}}\text{Cl}\left(\text{s}\right)\to {\text{NH}}_{\text{4}}\text{Cl}\left(\text{aq}\right)$ process should be calculated using the entropy values in the appendix L. It should be identifed that the sign of calculated ${\text{Δ}}_{\text{r}}{\text{S}}^{\text{o}}$ is in accordance with the predicted.

Concept introduction:

Entropy: Entropy is a measure of the randomness of the system. It is a thermodynamic quantity and an extensive property. It is represented by the symbol $\text{S}$. It can also be defined as the degree of energy dispersal. More the dispersal in energy, more is the value of entropy.

The standard entropy change for any reaction is the sum of standard molar entropies of product, subtracted from the sum of standard molar entropies of reactants. The standard molar entropies are multiplied by the stoichiometric coefficient which is as per the balanced equation.

  ${\text{Δ}}_{\text{r}}{\text{S}}^{\text{°}}\text{= }\sum {\text{nS}}^{\text{°}}\left(\text{products}\right)\text{-}\sum {\text{nS}}^{\text{°}}\left(\text{reactants}\right)$

(b)

Interpretation Introduction

Interpretation:

The standard entropy changes for the given ${\text{C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH}\left(\text{g}\right){\text{+3O}}_{\text{2}}\left(\text{g}\right)\to {\text{2CO}}_2\left(\text{g}\right)+{\text{3H}}_{\text{2}}\text{O}\left(\text{g}\right)$ process should be calculated using the entropy values in the appendix L. It should be identifed that the sign of calculated ${\text{Δ}}_{\text{r}}{\text{S}}^{\text{o}}$ is in accordance with the predicted.

Concept introduction:

Entropy: Entropy is a measure of the randomness of the system. It is a thermodynamic quantity and an extensive property. It is represented by the symbol $\text{S}$. It can also be defined as the degree of energy dispersal. More the dispersal in energy, more is the value of entropy.

The standard entropy change for any reaction is the sum of standard molar entropies of product, subtracted from the sum of standard molar entropies of reactants. The standard molar entropies are multiplied by the stoichiometric coefficient which is as per the balanced equation.

  ${\text{Δ}}_{\text{r}}{\text{S}}^{\text{°}}\text{= }\sum {\text{nS}}^{\text{°}}\left(\text{products}\right)\text{-}\sum {\text{nS}}^{\text{°}}\left(\text{reactants}\right)$