Thermodynamics and Chemistry

CHAPTER 6 THE THIRD LAW AND CRYOGENICS

PROBLEM 162

Problem

6.1 Calculate the molar entropy of carbon disulfide at25:00C and 1 bar from the heat capacity

data for the solid in Table6.2and the following data forp D 1 bar. At the melting point,

Table 6.2 Molar heat capacity

of CS 2 (s) atpD 1 bara

T=K Cp;m=J K^1 mol^1

15:05 6:9

20:15 12:0

29:76 20:8

42:22 29:2

57:52 35:6

75:54 40:0

94:21 45:0

108:93 48:5

131:54 52:6

156:83 56:6

aRef. [ 25 ].

161:11K, the molar enthalpy of fusion isÅfusHD4:39 103 J mol^1. The molar heat capac-

ity of the liquid in the range 161–300 K is described byCp;mDaCbT, where the constants

have the valuesaD74:6J K^1 mol^1 andbD0:0034J K^2 mol^1.