JEE Advance - Chemistry (2008 - Paper 1 Offline - No. 14)
Statement 1 : For every chemical reaction at equilibrium, standard Gibbs energy of reaction is zero.
and
Statement 2 : At constant temperature and pressure, chemical reactions are spontaneous in the direction of decreasing Gibbs energy.
Statement 1 is True, Statement 2 is True; Statement 2 is correct explanation for Statement 1.
Statement 1 is True, Statement 2 is True; Statement 2 is NOT correct explanation for Statement 1.
Statement 1 is True, Statement 2 is False.
Statement 1 is False, Statement 2 is True.
Explanation
The Gibbs free energy varies from standard value as a function of temperature and equilibrium constant.
$$\Delta$$G = $$\Delta$$G$$^\circ$$ + RT ln K$$_{eq}$$
The standard Gibbs energy for a reaction is given by $$\Delta$$G$$^\circ$$.
At equilibrium, $$\Delta$$G = 0whereas $$\Delta$$G$$^\circ$$ for a reaction may or may not be zero.
$$\Delta$$G$$^\circ$$ = $$-$$RT ln K$$_{eq}$$
For a spontaneous process, Gibbs energy for a reaction is always negative, $$\Delta$$G < 0.
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