For the reaction 2A+BrarrC at 298 K, DeltaH=400kJ mol^-1 and DeltaS=0.2 kJk^-1mol^_1. At what temperature will be reaction become spontaneous considering DeltaH and DeltaS to be constant over the temperature range.

For the reaction 2A+BrarrC at 298 K, DeltaH=400kJ mol^-1 and DeltaS=0.

1.	For the reaction 2A+BrarrC at 298 K, DeltaH=400kJ mol^-1 and DeltaS=0.2 kJk^-1mol^_1. At what temperature will be reaction become spontaneous considering DeltaH and DeltaS to be constant over the temperature range.
Answer» Solution :At equilibrium, `DeltaG`=0`therefore` DELTAH-TDELTAS`=0 or `DeltaH=TDeltaS` `therefore` T=`DeltaH/DeltaS=400/0.2=2000K` i.e the reaction will be at equilibrium at 2000K. Since `DeltaH`and `DeltaS` are positive`DeltaG` will be negative when `Tdeltas>DeltaH`. This takes PLACE at higher temperature. Therefore, the reaction will be sopntaneous at temperature above 2000K.