It is possible to perform a simple investigation into the thermodynamics of the stretching and contracting processes of a rubber band. It is recommended that you use a wide rubber band in order to get the best observations.
Quickly stretch the band until it is near full extension and place it in contact with a sensitive part of your skin (such as your lips or forehead). Answer the following questions:
(a) Does the stretched rubber band feel warmer or cooler?
(b) Has an exothermic or endothermic process occurred?
(c) The stretching of the rubber band is a non-spontaneous process because work was needed to carry it out. What sign does the Gibbs energy change of a non-spontaneous process have?
(d) Based upon your answers to (b) and (c), what is the sign of the entropy change when a rubber band is stretched?
(e) Think about the organisation of the polymer strands in a contracted and stretched rubber band. Draw a diagram for each and state which one is more ordered and therefore has the lower entropy.