Question

Problem 19.52 Three of the forms of elemental carbon are graphite, diamond, and buckminsterfullerene. The entropies at 298 K for graphite and diamond are C(s,graphite)=5.69J/mol?K, C(s,diamond)=2.43J/mol?K.

Part A Account for the difference in the S? values of graphite and diamond in light of their structures (Figure11.41 in the textbook). Essay answers are limited to about 500 words (3800 characters maximum, including spaces). 3800 Character(s) remaining SubmitMy AnswersGive Up Part B What would you expect for the S? value of buckminsterfullerene (Figure11.43 in the textbook) relative to the values for graphite and diamond? Explain.

Answer 1

The structure of diamond is diamond cubic, in which each carbon atom occupies a corner of a reegular tetrahedral and they are linked through sigma bond (sp3 hybridization). However, in graphite, the C atoms occupy corners of a hexagon and planar. Each planar sheets are linked via pi bonds (sp2 hybridization). Therefore, the movements of C atoms in graphite is less restricted than those in diamond and the atoms are more 'ordered' than the atoms in graphite. Hence the entropy of graphite is higher than that of diamond.

The entropy of fullerene is expected to be higher than graphite because C60 structure is less compact and less ordered than graphite.