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This post was last edited by wgqmqez on 2016-5-18 22:19. Basics of Inorganic Chemistry 09: “Physical Properties of Nitrogen”. Nitrogen, with the chemical formula N2, is a colorless and odorless gas under normal conditions; it is generally non-toxic as well. Usually, nitrogen has a lower density than air. Nitrogen accounts for 78.12% of the total atmosphere by volume, making it the main component of air. At standard atmospheric pressure, it turns into a colorless liquid when cooled to -195.8°C, and when cooled to -209.8°C, liquid nitrogen becomes a snow-like solid. Nitrogen has inert chemical properties and finds it difficult to react with other substances at room temperature; however, under high temperature and high-energy conditions, it can undergo chemical reactions with certain substances to produce new materials that are useful to humans. Physical properties: At normal conditions, nitrogen is a colorless and odorless gas that is insoluble in water and is generally non-toxic. Nitrogen accounts for 78.12% of the total volume of air (by volume), and its density under standard conditions is 1.25 g/L, which is slightly less than that of air. Nitrogen is insoluble in water; at normal temperature and pressure, about only 0.02 volumes of nitrogen dissolve in 1 volume of water. Nitrogen is a gas that is difficult to liquefy. At extremely low temperatures, nitrogen liquefies into a colorless liquid; further reduction in temperature results in the formation of a white crystalline solid. In production, black cylinders are typically used to store nitrogen. Other physical properties are shown in the table below: Item, Chemical formula, Relative molecular mass, CAS registry number, EINECS registry number, English name, Melting point, Boiling point at 101.325 kPa (1 atm), Critical temperature, Critical pressure, Critical volume, Critical density, Critical compressibility factor, Liquid density at –180°C, Coefficient of thermal expansion of the liquid at –180°C, Surface tension at –210°C, Gas density at 101.325 kPa (atm) and 70°F (21.1°C), Relative density of the gas at 101.325 kPa (1 atm) and 70°F (air = 1), Heat of vaporization, Heat of fusion at the boiling point, Constant-pressure specific heat capacity of the gas at 25°C, Constant-volume specific heat capacity of the gas at 25°C, Specific heat capacity ratio cp/cv, Specific heat capacity of the liquid at –183°C, Specific heat capacity of the solid at –223°C, Solubility parameter, Molar volume in water, Solubility at 25°C, Viscosity of the gas at 25°C, Viscosity of the liquid at –150°C, Thermal conductivity of the gas at 25°C, Thermal conductivity of the liquid at –150°C. Properties: N2, 28.0137727, -37-9, 231-783-9; Nitrogen, 63.15, K, -210°C, 77.35 K, -195.8°C, 126.1 K, -147.05°C, 3.4 MPa, 33.94 bar, 33.5 atm, 492.26 psia, 90.1 cm/mol, 0.3109 g/cm³, 0.2920, 0.729 g/cm³, 0.00753 1/°C, 12.2×10^-3 N/m, 12.2 dyn/cm, 1.160 kg/m³, 0.0724 lb/ft³, 0.9672, 2.76 kJ/kg, 87.19 BTU/lb, 25.7 kJ/kg, 11.05 BTU/lb, 1.038 kJ/(kg·K), 0.248 BTU/(lb·R), 0.741 kJ/(kg·K), 0.177 BTU/(lb·R), 1.401, 1.213 kJ/(kg·K), 0.509 BTU/(lb·R), 1.489 kJ/(kg·K), 0.356 BTU/(lb·R), 9.082 (J/cm), 0.534, 4.677 cm/mol, 17.28×10^-6 (w), 175.44×10^-7 Pa·s, 17.544 μPa·s, 0.038 mPa·s, 0.038 cp, 0.02475 W/(m·K), 0.0646 W/(m·K)