PHYSICAL CHEMISTRY IN BRIEF

CHAP. 6: THERMODYNAMICS OF HOMOGENEOUS MIXTURES [CONTENTS] 141

in which case equations (6.3) to (6.9) apply, or, more often, from the properties of the gas at
the temperature of the system and standard pressure, in which case we have

Hm,id.mix =

∑k

i=1

xiHm◦,i, (6.11)

Um,id.mix =

∑k

i=1

xiUm◦,i, (6.12)

CVm,id.mix =

∑k

i=1

xiCVm◦ ,i, (6.13)

Cpm,id.mix =

∑k

i=1

xiCp◦m,i, (6.14)

Sm,id.mix =

∑k

i=1

xiS◦m,i−Rln

p

pst

−R

∑k

i=1

xilnxi, (6.15)

Gm,id.mix =

∑k

i=1

xiG◦m,i+RTln

p

pst

+RT

∑k

i=1

xilnxi, (6.16)

Fm,id.mix =

∑k

i=1

xiFm◦,i+RTln

p

pst

+RT

∑k

i=1

xilnxi. (6.17)

Example

If the molar quantities in equations (6.3) to (6.9) and (6.11) to (6.17) are the molar quantities

of an ideal mixture of ideal gases for a given temperature, pressure and composition, then both

sets of equations must lead to the same result. Prove that the difference in their form is caused

by conversion from different standard states.