code: def Cvg(self):
          r'''Gas-phase ideal-gas contant-volume heat capacity of the chemical at
          its current temperature, in units of [J/kg/K]. Subtracts R from
          the ideal-gas heat capacity; does not include pressure-compensation
          from an equation of state.
  
          Examples
          --------
          >>> w = Chemical('water', T=520)
          >>> w.Cvg
          1506.1471795798861
          '''
          Cvgm = self.Cvgm
          if Cvgm:
              return property_molar_to_mass(Cvgm, self.MW)
          return Nonf Cvg(self):
          r'''Gas-phase ideal-gas contant-volume heat capacity of the chemical at
          its current temperature, in units of [J/kg/K]. Subtracts R from
          the ideal-gas heat capacity; does not include pressure-compensation
          from an equation of state.
  
          Examples
          --------
          >>> w = Chemical('water', T=520)
          >>> w.Cvg
          1506.1471795798861
          '''
          Cvgm = self.Cvgm
          if Cvgm:
              return property_molar_to_mass(Cvgm, self.MW)
          return None
docs: r'''Gas-phase ideal-gas contant-volume heat capacity of the chemical at
          its current temperature, in units of [J/kg/K]. Subtracts R from
          the ideal-gas heat capacity; does not include pressure-compensation
          from an equation of state.
  
          Examples
          --------
          >>> w = Chemical('water', T=520)
          >>> w.Cvg
          1506.1471795798861