code: def Am(self):
          r'''Helmholtz energy of the chemical at its current temperature and
          pressure, in units of [J/mol].
  
          This property requires that :obj:`thermo.chemical.set_thermo` ran
          successfully to be accurate.
          It also depends on the molar volume of the chemical at its current
          conditions.
          '''
          return self.Um - self.T*self.Sm if (self.Um is not None and self.Sm is not None) else Nonf Am(self):
          r'''Helmholtz energy of the chemical at its current temperature and
          pressure, in units of [J/mol].
  
          This property requires that :obj:`thermo.chemical.set_thermo` ran
          successfully to be accurate.
          It also depends on the molar volume of the chemical at its current
          conditions.
          '''
          return self.Um - self.T*self.Sm if (self.Um is not None and self.Sm is not None) else None
docs: r'''Helmholtz energy of the chemical at its current temperature and
          pressure, in units of [J/mol].
  
          This property requires that :obj:`thermo.chemical.set_thermo` ran
          successfully to be accurate.
          It also depends on the molar volume of the chemical at its current
          conditions.