Physical Chemistry Third Edition

1120 26 Equilibrium Statistical Mechanics. II. Statistical Thermodynamics

liquid hydrogen the molecules rotate freely. (This seems

to be an accurate assumption.)

a.Construct an accurate graph of the molar rotational

energy ofpara-hydrogen (restricted to even values of

J) from 0 K to 500 K. Sum up the rotational partition

function explicitly, including rotational states

up toJ6.

b.Construct an accurate graph of the molar rotational

heat capacity ofpara-hydrogen from 0 K to 500 K.

Explain in physical terms why the heat capacity

exhibits a maximum and compare your values with

the value of 8.3145 J K−^1 mol−^1 from Eq. (26.2-10c).

26.41Identify the following statements as either true or false. If
a statement is true only under special circumstances, label
it as false.

a.Statistical thermodynamic calculations for

monatomic gases are generally more accurate than

those for molecular gases.

b.The identification of statistical entropy and

thermodynamic entropy gives agreement with

experimental and statistical thermodynamic values

for dilute gases.

c.An isomerization reaction must have an equilibrium

constant equal to unity.

d.Values of standard-state thermodynamic functions of

gases calculated with statistical mechanics are always

less reliable than experimental values.