Sulfur trioxide is produced industrially by combining sulfur dioxide with oxygen

CHEMISTRY · Multi-part · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

Sulfur trioxide is produced industrially by combining sulfur dioxide with oxygen. Thermodynamic data at 298 K298\,\text{K} are given below: Reaction A S(s, rhombic)+O2(g)→SO2(g)S(\text{s, rhombic}) + O_2(\text{g}) \rightarrow \text{SO}_2(\text{g}) ΔSA∘=+248.2 J mol−1 K−1\Delta S^\circ_A = +248.2\,\text{J mol}^{-1}\,\text{K}^{-1} Reaction B S(s, rhombic)+1.5 O2(g)→SO3(g)S(\text{s, rhombic}) + 1.5\,O_2(\text{g}) \rightarrow \text{SO}_3(\text{g}) ΔSB∘=+256.8 J mol−1 K−1\Delta S^\circ_B = +256.8\,\text{J mol}^{-1}\,\text{K}^{-1} Using these data, analyze the conversion 2 SO2(g)+O2(g)→2 SO3(g)2\,\text{SO}_2(\text{g}) + O_2(\text{g}) \rightarrow 2\,\text{SO}_3(\text{g}) (Target Reaction) (a) Determine the standard entropy change ΔS∘\Delta S^\circ for the Target Reaction at 298 K298\,\text{K}. (b) Without additional calculation, predict the sign (positive, negative, or approximately zero) of ΔS∘\Delta S^\circ for the Target Reaction by considering only the change in the total amount of gaseous substance. Explain your reasoning. (c) Compare the numerical result from part (a) with your qualitative prediction in part (b). Discuss any agreement or discrepancy.

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