(A) For a spontaneous reaction,the Gibbs free energy change $ \Delta G $ must be negative,where $ \Delta G = \Delta H - T \Delta S $.If $ \Delta H $ i

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$ \Delta H $ value is positive and $ \Delta S $ value is negative

(A) For a spontaneous reaction,the Gibbs free energy change $ \Delta G $ must be negative,where $ \Delta G = \Delta H - T \Delta S $.If $ \Delta H $ is positive and $ \Delta S $ is negative,then $ \Delta G = (+ \Delta H) - T(- \Delta S) = + \Delta H + T \Delta S $.Since both terms are positive,$ \Delta G $ will always be positive regardless of the temperature $ T $.Therefore,the reaction cannot occur spontaneously under any conditions.

Class 11 Chemistry Thermodynamics Free energy and Work

Easy

$A$ chemical reaction cannot occur at all if

A
$ \Delta H $ value is positive and $ \Delta S $ value is negative
B
$ \Delta H $ value is negative and $ \Delta S $ value is positive
C
$ \Delta H $ and $ \Delta S $ values are negative but $ \Delta H > T \Delta S $
D
$ \Delta H $ and $ \Delta S $ values are positive but $ \Delta H > T \Delta S $

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Class 11 Questions

Class 11

Chemistry Questions

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Thermodynamics

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Free energy and Work

At what temperature $(T \ K)$ will the reaction be in equilibrium (in $K$)? $Ag_2O_{(s)} \rightarrow 2Ag_{(s)} + \frac{1}{2} O_{2(g)}$,given $\Delta H = 30.5 \ kJ \ mol^{-1}$ and $\Delta S = 0.066 \ kJ \ K^{-1} \ mol^{-1}$.

Medium

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For the reaction $H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}$,$\Delta H = -285.8 \ kJ \ mol^{-1}$,$\Delta S = -0.163 \ kJ \ mol^{-1} K^{-1}$. What is the value of free energy change at $27 \ ^\circ C$ for the reaction in $kJ \ mol^{-1}$?

Medium

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For the reaction $C_{(graphite)} + CO_{2(g)} \rightarrow 2CO_{(g)}$,$\Delta H = 170 \ kJ$ and $\Delta S = 170 \ J/K$. At what temperature $(K)$ will the reaction become spontaneous?

Medium

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For vaporization of water at $1$ atmospheric pressure,the values of $\Delta H$ and $\Delta S$ are $40.63 \ kJ \ mol^{-1}$ and $108.8 \ J \ K^{-1} \ mol^{-1},$ respectively. The temperature when Gibb's energy change $(\Delta G)$ for this transformation will be zero,is ............ $K$. (in $.4$)

MediumAIPMT 2010

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For reaction $Ag_2O_{(s)} \to 2Ag_{(s)} + 1/2 O_{2(g)}$,the value of $\Delta H = 30.56 \ kJ \ mol^{-1}$ and $\Delta S = 0.066 \ kJ \ K^{-1} \ mol^{-1}$. Temperature at which free energy change for reaction will be zero,is ............. $K$.

Medium

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$A$ chemical reaction cannot occur at all if

Similar Questions

At what temperature $(T \ K)$ will the reaction be in equilibrium (in $K$)? $Ag_2O_{(s)} \rightarrow 2Ag_{(s)} + \frac{1}{2} O_{2(g)}$,given $\Delta H = 30.5 \ kJ \ mol^{-1}$ and $\Delta S = 0.066 \ kJ \ K^{-1} \ mol^{-1}$.

For the reaction $H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}$,$\Delta H = -285.8 \ kJ \ mol^{-1}$,$\Delta S = -0.163 \ kJ \ mol^{-1} K^{-1}$. What is the value of free energy change at $27 \ ^\circ C$ for the reaction in $kJ \ mol^{-1}$?

For the reaction $C_{(graphite)} + CO_{2(g)} \rightarrow 2CO_{(g)}$,$\Delta H = 170 \ kJ$ and $\Delta S = 170 \ J/K$. At what temperature $(K)$ will the reaction become spontaneous?

For vaporization of water at $1$ atmospheric pressure,the values of $\Delta H$ and $\Delta S$ are $40.63 \ kJ \ mol^{-1}$ and $108.8 \ J \ K^{-1} \ mol^{-1},$ respectively. The temperature when Gibb's energy change $(\Delta G)$ for this transformation will be zero,is ............ $K$. (in $.4$)

For reaction $Ag_2O_{(s)} \to 2Ag_{(s)} + 1/2 O_{2(g)}$,the value of $\Delta H = 30.56 \ kJ \ mol^{-1}$ and $\Delta S = 0.066 \ kJ \ K^{-1} \ mol^{-1}$. Temperature at which free energy change for reaction will be zero,is ............. $K$.

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