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Thermodynamics — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryThermodynamics5 Marks
Question
For the reaction, 2A(g) + B(g) → 2D(g)$\Delta\text{U}^\ominus=-10.5\text{kJ} \ \text{and} \ \Delta\text{S}^\ominus=-44.1\text{kJ}^{-1}.$
Calculate $\Delta\text{G}^\ominus$ for the reaction, and predict whether the reaction may occur spontaneously.
✓

Answer

For the given reaction, $2 A_{( g )}+ B _{( g )} \rightarrow 2 D _{( g )} \Delta ng _{ g }=2-(3)$
$=-1$ mole Substituting the value of $\Delta U ^{\ominus}$ in the expression of $\Delta H : \Delta H ^{\ominus}=\Delta U ^{\ominus}+\Delta ng _{ g } RT$
$=(-10.5 kJ)-(-1)\left(8.314 \times 10^{-3} kJ K ^{-1} mol^{-1}\right)(298 K)=-10.5 kJ-2.48 kJ \Delta G ^{\ominus}=+0.16 kJ$
Since $\Delta G ^{\ominus}$ for the reaction is positive, the reaction will not occur spontaneously.

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