Density and Viscosity of Liquid ND3

The density and viscosity of liquid ND₃ have been measured over the temperature range from $\text{+30°}$ to $\text{−25°}$ and compared with the density and viscosity of liquid NH₃. At any given temperature, the ratio of densities ρND₃/ρNH₃ is $\text{1.187± 0.001}$ and the ratio of viscosities ηND₃/ηNH₃ is $\text{1.20± 0.01}$ . The fact that both ratios are independent of temperature suggests that the strengths of intermolecular interactions are essentially the same in the two liquids and that the density and viscosity differences are to be attributed to differences in molecular size and mass. The density ratio indicates that the molecular volume of NH₃ in the liquid is $\text{∼ 1\%}$ larger than that of ND₃ while the viscosity ratio indicates that the viscosity varies directly as M/V_m (V_m=molar volume) for these two liquids.