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Question: Answered & Verified by Expert
A reaction is spontaneous at all temperature, when
ChemistryThermodynamics (C)COMEDKCOMEDK 2019
Options:
  • A $\Delta H$ is -ve and $\Delta S$ is + ve
  • B $\Delta H$ is + ve and $\Delta S$ is - ve
  • C Both $\Delta H$ and $\Delta S$ are - ve
  • D Both $\Delta H$ and $\Delta S$ are $+v e$
Solution:
2031 Upvotes Verified Answer
The correct answer is: $\Delta H$ is -ve and $\Delta S$ is + ve
For a reaction to be spontaneous change in Gibbs free energy should be negative.
i.e. $\Delta G=\Delta H-T \Delta S < 0$
$$
=(-v e)-(+v e)=-\text { e }-\text { ve }=-2 \mathrm{ve}
$$
$\Delta H < 0$ and $\Delta S>0$
So, $\Delta H=-$ ve and $\Delta S=+$ ve

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