Tamil Nadu Board of Secondary EducationHSC Science Class 11

The standard enthalpies of formation of SO2 and SO3 are −297 kJ mol−1 and −396 kJ mol−1 respectively. Calculate the standard enthalpy of reaction for the reaction: SOX2+12OX2⟶SOX3 - Chemistry

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Numerical

The standard enthalpies of formation of SO2 and SO3 are −297 kJ mol−1 and −396 kJ mol−1 respectively. Calculate the standard enthalpy of reaction for the reaction: \[\ce{SO2 + 1/2O2 -> SO3}\]

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Solution

`Δ"H"_"f"^0` (SO2) = −297 kJ mol−1

`Δ"H"_"f"^0` (SO3) = −396 kJ mol−1

\[\ce{SO2 + 1/2O2 -> SO3}\]

`Δ"H"_"r"^0` = ?

`Δ"H"_"r"^0 = (Δ"H"_"f"^0)_"compound" - sum(Δ"H"_"f")_"elements"`

`Δ"H"_"r"^0 = Δ"H"_"f"^0 ("SO"_3) - [Δ"H"_"f"^0 ("SO"_2) + 1/2 Δ"H"_"f"^0 ("O"_2)]`

`Δ"H"_"r"^0` = −396 kJ mol−1 − (−297 kJ mol−1 + 0)

`Δ"H"_"r"^0` = −396 kJ mol−1 + 297

`Δ"H"_"r"^0` = − 99 kJ mol−1

Concept: Enthalpy (H)
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Chapter 7: Thermodynamics - Evaluation [Page 227]

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Tamil Nadu Board Samacheer Kalvi Class 11th Chemistry Volume 1 and 2 Answers Guide
Chapter 7 Thermodynamics
Evaluation | Q II. 43. | Page 227

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