Concise Physical Chemistry

c05 JWBS043-Rogers September 13, 2010 11:25 Printer Name: Yet to Come

PROBLEMS AND EXAMPLE 83

Problem 5.8

TheCp/Tvs.Tdata set for solid lead Pb(s) is written in BASIC as follows:

DATA 0,0,5,.061,10,.28,15,.4666,20,.54,25,.564,30,.55,50,.428,

70,.333,100,.245,150,.169 200,.129,250,.105,298,.089

N = 14

The data are in 14 pairs. The first number of the pair isTand the second isCp.Devise

a program of your own or use a canned program to estimate the standard entropy of

Pb(s).

Problem 5.9

Phase changes occur reversibly. For example, the transition from solid ice to liquid

water, which occurs at a temperature that is infinitesimally above the melting point of

273.15 K, can be reversed by lowering the ambient temperature to slightly less than

273.15 K.

(a) The standard enthalpy of fusion
fusH◦is 6.01 kJ mol−^1. What is the entropy

of fusion,
fusS◦?

(b) The standard enthalpy of vaporization of water is
vapH◦= 40 .7kJmol−^1.

What is the entropy of vaporization of water,l→v?

(c) Why are the results so different?