Resources, Tools and Basic Information for Engineering and Design of Technical Applications!Custom Search Search - "the most efficient way to navigate!" Air - Molecular Weight Dry air is a mixture of gases where the average molecular weight (or molar mass) can be calculated by adding the weight of each component Sorry to see that you are blocking ads on The Engineering ToolBox! If you find this page valuable and appreciate it is open and free for everybody - please contribute by • disabling your adblocker on The Engineering ToolBox! •• How to? The molecular weight (or molar mass) of a substance is the mass of one mole of the substance, and can be calculated by summarizing the molar masses of all the atoms in the molecule. Components in Dry Air Air is a mixture of several gases, where the two most dominant components in dry air are oxygen and nitrogen. Oxygen has a molar mass of 16 g/mol and nitrogen has a molar mass of 14 g/mol. Since both of these elements are diatomic in air - O2 and N2, the molar mass of oxygen is 32 g/mol and the molar mass of nitrogen is 28 g/mol. Air is a mixture of gases, and the average molar mass is equal to the sum of the mole fractions of each gas multiplied by the molar mass of that particular gas: Mmixture = (x1*M1 + ......+ xn*Mn) (1) where xi = mole fractions of each gas Mi = the molar mass of each gas Molar Mass - M Molar Mass in Air Components in Dry Air Volume Ratio compared to Dry Air [g/mol] [g/mol] xygen 0.2095 32.00 6.704 Nitrogen 0.7809 28.02 21.881 Carbon dioxide 0.0003 44.01 0.013 Hydrogen 0.0000005 2.02 0 Argon 0.00933 39.94 0.373 Neon 0.000018 20.18 0 Helium 0.000005 4.00 0 Krypton 0.000001 83.8 0 Xenon 0.09 10-6 131.29 0 Average molar mass of air 28.971 1 kg = 2.2046 lb Air Density The density of dry air can be calculated with the Ideal Gas Law ρ = p / (R T) (1) where p = pressure (kPa) R = 286.9 = individual gas constant [J/kg K] T = absolute temperature [K] Example: The density of dry air at atmospheric pressure 101.325 kPa (101325 Pa) and 0 oC can be calculated as ρ = 101325 [Pa] / (286.9 [J/kg K]*273 [K]) = 1.294 [kg/m3] Water Vapor Water vapor is almost always present in air. The content may vary and the maximum amount possible of water vapor in dry air depends on the temperature of the air. Water vapor - H2O - is composed of one oxygen atom and two hydrogen atoms. Hydrogen is the lightest element with a molar mass of 1 g/mol, while oxygen has 16 g/mol. Thus, the water vapor atom has an molar mass of 18 g/mol, and water vapor is lighter than O2 with 32 g/mol and N2 with 28 g/mol. Note! Water vapor in air will dilute the other gases and reduce the total density of the mixture. Dry air is more dense than humid air! The vapor in air may saturate to droplets when temperature is decreased or pressure is increased. moist air - temperature and saturation pressure Humid air containing water molecules as liquid - droplets - may be more dense than dry air or humid air containing water only as vapor. Related Topics Air Psychrometrics - The study of moist and humid air - psychrometric charts, Mollier diagrams, air-condition temperatures and absolute and relative humidity and moisture content Material Properties - Material properties for gases, fluids and solids - densities, specific heats, viscosities and more Sorry to see that you are blocking ads on The Engineering ToolBox! If you find this page valuable and appreciate it is open and free for everybody - please contribute by • disabling your adblocker on The Engineering ToolBox! •• How to? Related Documents Dry Air and Water Vapor - Density and Specific Volume - Imperial Units - Density and specific volume of dry air and water vapor at temperatures ranging 225 to 900 degF (107 to 482 degC) Specific Heat Ratio of Air - Specific Heat Ratio of air at temperatures from -40 - 1000oC (-40 - 1500oF) at standard atmospheric pressure - Imperial and SI Units Humid Air and the Ideal Gas Law - Pressure, temperature and volume for an ideal or perfect gas like air with water vapor - or moist air Air - Temperature, Pressure and Density - Air density for pressure range 0 - 1000 psi and temperature range 30 - 600 deg F Air Composition - Dry air is a mechanical mixture of nitrogen, oxygen, carbon dioxide and more Density of Moist Humid Air - Density of dry air and water vapor - moist or humid air Mole Fraction of Water Vapor in Moist Air - Mole fraction of water vapor is the ratio of water molecules - to air and water molecules Gases - Molar Specific Heat - Molar specific heats of gases at constant volume Molecular Weight - Common Substances - Definition and molecular weight (molar mass) of some common substances Universal and Individual Gas Constants - The Universal and Individual Gas Constants in fluid mechanics and thermodynamics Gases - Density - Densities and molecular weights of some common gases - acetylene, air, methane, nitrogen, oxygen and others .. Ideal Gas Law - The relations between volume, pressure, temperature and quantity of a gas, including definition of density of a gas. Mole and Avagadro's Number - The mole is the SI base unit for amount of substance Dutch . . stairs and more .Select Your own language .SketchUp Extension/Plugin ."the most efficient way to navigate!" Engineering ToolBox .Portuguese .SketchUp Extension . All applicable national and local regulations and practices concerning this aspects must be strictly followed and adhered to. About the ToolBox We appreciate any comments and tips on how to make The Engineering ToolBox a better information source.Chemical.Listing of van der Waals constants for more than 200 gases.German .0 oC oF Convert! Length 1.Special care must be taken for gas mixtures when using the ideal gas law.Van der Waals equation and constants .N2 Gas Mixtures and Properties . Please contact us by email editor.How to calculate total pressure and partial pressures for gas mixtures from Ideal Gas Law Non-ideal gas .Chinese (Simplified) . thermal conductivity.enabled for use with the amazing. piping.0 m km in ft yards miles nautical miles Convert! Volume . The content in The Engineering ToolBox is copyrighted but can be used with NO WARRANTY or LIABILITY. dynamic viscosity. ratio of specific heats. density and kinematic viscosity Tag Search en: molecular mass air es: aire masa molecular de: Molekularmasse Luft Search the Engineering ToolBox Search .Chinese (Traditional) . Physical and Thermal Properties of Oxygen . This site use third-party cookies. lumbers.com if You find any faults.Chemical.French .to your SketchUp model with the Engineering ToolBox .Korean .O2 Nitrogen . the individual gas constant or the density Total and partial pressure . calculating the mass.Russian .like flange beams.Dalton's law of partial pressures . More info here. Prandtl number.engineeringtoolbox@gmail. Physical and Thermal Properties of Nitrogen . used to correct for non-ideal behavior of gases caused by intermolecular forces and the volume occupied by the gas particles Dry Air Properties . Home Acoustics Air Psychrometrics Basics Combustion Drawing Tools Dynamics Economics Electrical Environment Fluid Mechanics Gases and Compressed Air HVAC Systems Hydraulics and Pneumatics Insulation Material Properties Mathematics Mechanics Miscellaneous Physiology Piping Systems Process Control Pumps Standard Organizations Statics Steam and Condensate Thermodynamics Water Systems Unit Converter Temperature 0.Dry air properties at temperatures ranging 175 . or otherwise unacceptable information. fun and free SketchUp Make and SketchUp Pro .1900 K .Online 3D modeling! Add standard and customized parametric components .. Important information should always be double checked with alternative sources.Italian .specific heat.Japanese . inaccuracies. Oxygen .Spanish . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse! Translate the ToolBox Arabic . 0 m3/s m3/h US gpm cfm Convert! Scientific Online Calculator 9-13 Share this Page! 78 39 Shortcut to Home Screen? The Engineering ToolBox bimSystems .0 kgf N lbf Convert! Velocity 1. 1.0 Pa (N/m2) bar mm H2O kg/cm2 psi inches H2O Convert! Flow 1.tracking and sharing expenses between participants! .0 m/s km/h ft/min ft/s mph knots Convert! Pressure 1.with tickets! the Travlet .organizing design and development of technical systems! mee icketst .0 m3 liters in3 ft3 us gal Convert! Weight 1.summarize meetings and keep track of tasks to be done .