(Solved):   Chapter 12 Calculating entropy change from reversible heat flow The heat of fusion \( \D ...

 

Chapter 12 Calculating entropy change from reversible heat flow The heat of fusion \( \Delta \mathrm{H}_{f} \) of dichloromethane \( \left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right) \) is \( 6.2 \mathrm{~kJ} / \mathrm{mol} \). Calculate the change in entropy \( \Delta S \) when \( 35 . \mathrm{g} \) of dichloromethane melts at \( -95.1{ }^{\circ} \mathrm{C} \). Be sure your answer contains a unit symbol and the correct number of significant digits. Using the Second Law to predict spontaneous change Read the descriptions of physical or chemical changes in the table below. Then decide whether the change will be spontaneous, if you can. \begin{tabular}{|l|l|} \hline \multicolumn{1}{|c|}{ Change } & Is this change spontaneous? \\ \hline During an exothermic chemical reaction, a solid is consumed and a gas \\ produced. \end{tabular} For each system listed in the first column of the table below, decide (if possible) whether the change described in the second column will increase the entropy \( S \) of the system, decrease \( S \), or leave \( S \) unchanged. If you don't have enough information to decide, check the "not enough information" button in the last column. Predicting qualitatively how entropy changes with mixing and separation For each system Ilsted in the first column of the table below, decide (If posslble) whether the change described in the second column will Increase the entropy \( S \) of the system, decrease \( S \), or leave \( S \) unchanged. If you don't have enough information to decide, check the "not enough information" button in the last column. Note for advanced students: you may assume ideal gas and ideal solution behaviour.