Can reaction that is endothermic with a decrease in entropy occur spontaneously? Why?
1 Answer
No.
An endothermic process absorbs energy into the system. If its entropy then decreases, then the system has tried to condense that energy further.
Energy naturally wants to spread out, so if you compress it and add more and more energy in, the system is going to want to spread the energy out and get rid of it.
Another way to view this is from the Gibbs' isothermal relation:
#DeltaG = DeltaH - TDeltaS# where
#G# is the Gibbs' free energy,#H# is enthalpy, and#S# is entropy.
When the process is endothermic with respect to the system,
#overbrace(DeltaG_(sys))^(???) = overbrace(DeltaH_(sys))^((+)) - overbrace(T)^((+))cdot overbrace(DeltaS_(sys))^((-))#
And a positive minus a negative is always positive. Thus, this process is always nonspontaneous, since
