These two expressions are two versions of the virial equation of state.1 By comparing the expression with eqn 1.18 we see that the term in parentheses in eqn 1.19b is just the compression factor, Z.
These two expressions are two versions of the virial equation of state.1 By comparingthe expression with eqn 1.18 we see that the term in parentheses in eqn 1.19b is just thecompression factor, Z.