Evaporation is an endothermic process undertaken by all liquids. This physical state change occurs when surface molecules gain sufficient kinetic energy to overcome the enthalpy of vaporization.

Introduction Two dry solids --- barium hydroxide and ammonium nitrate --- are mixed to produce an endothermic reaction. The temperature of the mixture drops approximately 45oC and is cold enough to ...

The cooling effect means that it is an endothermic process (D H>0) so that TD S is positive. Thus the entropy of the rubber band increases when it goes from the stretched state to the natural state.