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Supposc that two systems, cach composed of two particles representedby circles, have 20 $\mathrm{J}$ of total cnergy. Which system, $\mathrm{A}$ or $\mathrm{B},$ has thegreater entropy? Why?
Rank each set of substances in order of increasing standard molar entropy $\left(S^{\circ}\right) .$ Explain your reasoning.\begin{equation}\begin{array}{l}{\text { a. } \mathrm{I}_{2}(s) ; \mathrm{F}_{2}(g) ; \mathrm{Br}_{2}(g) ; \mathrm{Cl}_{2}(g)} \\ {\text { b. } \mathrm{H}_{2} \mathrm{O}(g) ; \mathrm{H}_{2} \mathrm{O}_{2}(g) ; \mathrm{H}_{2} \mathrm{S}(g)}\end{array} \end{equation}c. C(s, graphite); C(s, diamond); C(s, amorphous)
Use data from Appendix IVB to calculate $\Delta S_{\mathrm{mn}}^{\circ}$ for each of the reactions. In each case, try to rationalize the sign of $\Delta S_{\mathrm{rm}}^{\mathrm{a}}$\begin{equation}\begin{array}{l}{\text { a. } C_{2} \mathrm{H}_{4}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{6}(g)} \\ {\text { b. } \mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_{2}(g)}\end{array} \end{equation}\begin{equation}\begin{array}{l}{\text { c. } \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{H}_{2}(g)+\mathrm{CO}_{2}(g)} \\ {\text { d. } 2 \mathrm{H}_{2} \mathrm{S}(g)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{SO}_{2}(g)}\end{array} \end{equation}
Use data from Appendix IVB to calculate $\Delta S_{\mathrm{ron}}^{\circ}$ for each of the reactions. In each case, try to rationalize the sign of $\Delta H_{\mathrm{rxn}}^{\circ}$\begin{equation}\begin{array}{l}{\text { a. } 3 \mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow 2 \mathrm{HNO}_{3}(a q)+\mathrm{NO}(g)} \\ {\text { b. } \mathrm{Cr}_{2} \mathrm{O}_{3}(s)+3 \mathrm{CO}(g) \longrightarrow 2 \mathrm{Cr}(s)+3 \mathrm{CO}_{2}(g)}\end{array} \end{equation}\begin{equation}\begin{array}{l}{\text { c. } \mathrm{SO}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{SO}_{3}(g)} \\ {\text { d. } \mathrm{N}_{2} \mathrm{O}_{4}(g)+4 \mathrm{H}_{2}(g) \longrightarrow \mathrm{N}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)}\end{array} \end{equation}
Find $\Delta S^{\circ}$ for the formation of $\mathrm{CH}_{2} \mathrm{Cl}_{2}(g)$ from its gascous elements in their standard states. Rationalize the sign of $\Delta S^{\circ} .$
Without doing any calculations, determine the sign of $\Delta S_{y y}$ and$\Delta S_{\text { surt }}$ for each chemical reaction. In addition, predict under what tem-peratures (all temperatures, low temperatures, or high temperatures), ifany, the reaction is spontaneous.$\mathrm{a} \cdot \mathrm{C}_{3} \mathrm{H}_{8}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 3 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$$\Delta H_{\mathrm{rum}}^{\circ}=-2044 \mathrm{kJ}$$\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{NO}(g) \quad \Delta H_{\mathrm{m} m}^{\mathrm{o}}=+182.6 \mathrm{kJ}$$2 \mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{N}_{2} \mathrm{O}(g) \quad \Delta H_{\mathrm{ran}}^{\circ}=+163.2 \mathrm{kJ}$$4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$$\Delta H_{\mathrm{rm}}^{\circ}=-906 \mathrm{kJ}$
