Lawrie Ryan and Roger Norris Solutions for Chapter: Entropy and Gibbs Free Energy, Exercise 14: EXAM-STYLE QUESTIONS

For the following reaction, state whether the entropy of the system decreases or increases. Explain your answer in terms of the order or disorder of the particles.

$\mathrm{NaCl}\left(\mathrm{s}\right)+\mathrm{aq}\to {\mathrm{Na}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)$.

For the following reaction: State whether the entropy of the system decreases or increases. Explain your answer in terms of the order or disorder of the particles.

The table shows the formula, state, and standard molar entropies of the first five straight-chain alkanes.

Describe and explain the trend in the standard molar entropies of these alkanes.

The table shows the formula, state, and standard molar entropies of the first five straight-chain alkanes.

Estimate the value of the standard molar entropy of the straight-chain alkane with the formula.

Write a balanced equation to represent the standard free energy change of formation of ethane. Include state symbols in your answer.

The standard free energy change of formation of ethane is $-32.9 \mathrm{kJ} {\mathrm{mol}}^{-1}.$ The standard entropy change of the system for this reaction is $-173.7 \mathrm{J} {\mathrm{K}}^{-1} {\mathrm{mol}}^{-1}.$.

State the relationship between standard free energy change of formation, standard entropy change of the system, and enthalpy change.

The standard free energy change of formation of ethane is $-32.9 \mathrm{kJ} {\mathrm{mol}}^{-1}.$ The standard entropy change of the system for this reaction is $-173.7 \mathrm{J} {\mathrm{K}}^{-1} {\mathrm{mol}}^{-1}.$

Explain why the reaction can be feasible, even though the value of the standard entropy change of the system is negative.

Ethane undergoes combustion to form carbon dioxide and water.

${\mathrm{C}}_2{\mathrm{H}}_6\left(\mathrm{g}\right)+\frac{7}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{CO}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Calculate the free energy change of combustion for this reaction.

$$\begin{gathered} \mathrm{Values} \mathrm{of} ∆{\mathrm{G}}_{\mathrm{f}}^{⊝} \mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}: \\ {\mathrm{C}}_2{\mathrm{H}}_6\left(\mathrm{g}\right)=-32.9, {\mathrm{CO}}_2\left(\mathrm{g}\right)=-394.4, {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)=-237.2. \end{gathered}$$