Compressibility factor, Z, of a gas is given as Z = PV/ nRT

(i) What is the value of Z for an ideal gas?

(ii) For real gas what will be the effect on value of Z above Boyle’s temperature?

(i) Compressibility factor, Z is defined as the ratio of the product of pressure and volume to the product of number of moles, gas constant and temperature.

For ideal gas, the value of Z is 1.

Because, we know according to ideal gas equation,

PV = nRT

So, Z =

=

= 1

(ii) As at the temperature which is above the Boyle’s temperature, PV is greater than nRT for real gases so, the value of Z will also be greater than 1 i.e Z>1, which shows the positive deviation in the compressibility factor above Boyle’s temperature.