Heat capacity values of Se5 g at

02604 X 10 T ) J-K -mol was derived by the review from the mean of the heat capacity expressions for Se4(g) and Sc6(g) (cf Sections V.1.7 and V.1.9). The heat capacity calculated from this expression and that in [74M1L] differ by less than 0.1 J K mor in the temperature range 750 to 1500 K and amounts to a maximum of 0.45 J K mor at 298.15 K. The expression was employed in recalculations and evaluations wherever the thermodynamic properties of Ses(g) were required at other temperatures than the standard temperature. The heat capacity at 298.15 K calculated from the expression is C° ,(Se5, g, 298.15 K) = (100.8 3.0) J-K -mor. No value of the heat capacity is selected because all tentative values are based on estimated quantities only. 

The third law evaluations made in this review reduce the scatter of the enthalpy values by more than 50%. The scatter of the values obtained from the second law is an effect of the small temperature ranges used in most of the studies. The second law value in [75HOA/REY] for the equilibrium with liquid selenium is not included in the average in Table V-12 because it stems from measurements which result in an enthalpy of fusion of selenium that is twice as large as the correct value. 

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