Compressibility Factor Charts

n-hexane

carbon dioxide

ethane

nitrogen

hydrogen

The compressibility factor chart plots the compressibility factor

Z

, equal to

PV

RT

, where

V

is the volume per mole, versus the reduced pressure

P

r

for several values of the reduced temperature

T

r

. The reduced pressure and temperature are defined by

P

r

=P/

P

c

and

T

r

=T/

T

c

, respectively, where

P

c

is the critical pressure and

T

c

is the critical temperature. Use buttons to select one of five molecules, and move the black dot to display the compressibility factor curve (blue) for any value of

T

r

between 1.0 and 1.8. The

Z

and

P

r

values for the location of the black dot are displayed on the chart. For an ideal gas,

Z=1

(green line).