It is quite common for a solid to change from one structure to another at a temperature below its melting point. For example, sulfur undergoes a phase change from the rhombic crystal structure to the monoclinic crystal form at temperatures above $95^{\circ} \mathrm{C}$. a. Predict the signs of $\Delta H$ and $\Delta S$ for the process $S_{\text {thombic }} \longrightarrow$ $\mathrm{S}_{\text {monelinie- }}$ b. Which form of sulfur has the more ordered crystalline structure?

          It is quite common for a solid to change from one structure to another at a temperature below its melting point. For example, sulfur undergoes a phase change from the rhombic crystal structure to the monoclinic crystal form at temperatures above $95^{\circ} \mathrm{C}$.
a. Predict the signs of $\Delta H$ and $\Delta S$ for the process $S_{\text {thombic }} \longrightarrow$ $\mathrm{S}_{\text {monelinie- }}$
b. Which form of sulfur has the more ordered crystalline structure?

Added by Hugo R.

Chemistry: Structure and Properties

Nivaldo Tro 2nd Edition

Instant Answer

Solved by Expert Shaiju T

04/22/2022

Step 1

Since this is a solid-solid phase transition below the melting point, there is no change in the number of moles of the substance. Therefore, $\Delta H$ will be positive (endothermic) as energy is required to break and reform the crystal lattice in the phase Show more…

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It is quite common for a solid to change from one structure to another at a temperature below its melting point. For example, sulfur undergoes a phase change from the rhombic crystal structure to the monoclinic crystal form at temperatures above $95^{\circ} \mathrm{C}$. a. Predict the signs of $\Delta H$ and $\Delta S$ for the process $S_{\text {thombic }} \longrightarrow$ $\mathrm{S}_{\text {monelinie- }}$ b. Which form of sulfur has the more ordered crystalline structure?