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JEE Main 202524 JanuaryEvening Shift
Exam
JEE Main
Year
2025
Date
24 January
Shift
Evening Shift
Subject
Chemistry
Chapter
Thermodynamics (C)

JEE Main 2025 · 24 January · Evening Shift · Chemistry · Thermodynamics (C)

aligned & S(~g)+(3)/(2) O_2(~g) arrow SO_3(~g)+2 x kcal &...

S( g)+32O2( g)→SO3( g)+2xkcalSO2( g)+12O2( g)→SO3( g)+ykcal\begin{aligned} & \mathrm{S}(\mathrm{~g})+\frac{3}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+2 x \mathrm{kcal} \\ & \mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+y \mathrm{kcal} \end{aligned} The heat of formation of SO2( g)\mathrm{SO}_2(\mathrm{~g}) is given by :

Options

  1. Ax+ykcalx+y \mathrm{kcal}
  2. By−2xkcaly-2 x \mathrm{kcal}
  3. C2xykcal\frac{2 x}{y} \mathrm{kcal}
  4. D2x+ykcal2 x+y \mathrm{kcal}

Correct answer

B. y−2xkcaly-2 x \mathrm{kcal}

Step-by-step solution

(i) S(g)+32O2( g)→SO3( g)+2x\mathrm{S}(\mathrm{g})+\frac{3}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+2 x kcal ΔH1\Delta \mathrm{H}_1 (ii) SO2( g)+12O2( g)→SO3( g)+y\mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+y kcal ΔH2\Delta \mathrm{H}_2 (i) - (ii) S( g)+O2( g)→SO2( g)ΔHΔH=ΔH1−ΔH2=−2x−(−y)=(y−2x)kcal\begin{aligned} & \mathrm{S}(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_2(\mathrm{~g}) \Delta \mathrm{H} \\ & \Delta \mathrm{H}=\Delta \mathrm{H}_1-\Delta \mathrm{H}_2 \\ & =-2 x-(-y)=(y-2 x) \mathrm{kcal} \end{aligned}
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