code: def Zg_STP(self):
          r'''Gas-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['nitrogen'], ws=[1]).Zg_STP
          0.9995520809691023
          '''
          Vmg = self.Vmg
          if Vmg:
              return Z(self.T, self.P, Vmg)
          return Nonf Zg_STP(self):
          r'''Gas-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['nitrogen'], ws=[1]).Zg_STP
          0.9995520809691023
          '''
          Vmg = self.Vmg
          if Vmg:
              return Z(self.T, self.P, Vmg)
          return None
docs: r'''Gas-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['nitrogen'], ws=[1]).Zg_STP
          0.9995520809691023