The value of DeltaH and DeltaS for the reaction C_("(graphite)")+CO_92)(g) rarr 2CO(g0 are170 kJ and 170JK^(-1) respectively. This reaction will be spontaneous at

The value of DeltaH and DeltaS for the reaction C_("(graphite)")+CO_92

1.	The value of DeltaH and DeltaS for the reaction C_("(graphite)")+CO_92)(g) rarr 2CO(g0 are170 kJ and 170JK^(-1) respectively. This reaction will be spontaneous at
Answer» 910 K 1110K 510K 710 K Solution :`DeltaG =DeltaH - T DeltaS`. For reaction to be spontaneous `DeltaS` should be -ve, i.e.,`DeltaH-TDetlaS lt0 `or `DeltaHlt T DeltaS` or `TDeltaS gt DeltaH ` or`Tgt ( DeltaH )/( DeltaS) , i.e.,T gt (170000J)/( 170 JK^(-1))`or `T gt 1000K`. Hence, options (b) ISCORRECT. This method can be APPLIED only when `DeltaH` and`DeltaS` both are `+ve`. Alternatively, for equilibrium, `DeltaG =0` `i.e., T DeltaS = DeltaH` or `T= ( DeltaH )/( DeltaS) =( 170000)/( 170) =1000K` For spontaneity , `DeltaG = -ve`which can be so if `T gt 1000 K` ( so that`T DeltaS gt DetalH` in magnitude ) .