The entropy of a substance often gives a clue about its structure, including how its molecules are arranged in a solid. The entropy of 1.00 mol FClO₃(s) at T = 0 is 10.1 J · K^–1. Suggest an interpretation.

ANTICIPATE The observation that the entropy is nonzero at T = 0 suggests that the molecules are positionally disordered at that temperature.

PLAN From the shape of the molecule, determine how many orientations, W, it is likely to be able to adopt in a crystal; then use the Boltzmann formula to see whether that number of orientations leads to the observed value of S.