Enter your gas's Pressure, Temperature, Molecular Weight, and Compressibility Factor (Z) into the Gas Density Calculator, and it returns the Gas Density along with Specific Volume and Density in g/L — handy when Z strays from 1 and ideal gas assumptions just won't cut it.
Gas Density
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Specific Volume
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Density (g/L)
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Gas density is the mass of gas per unit volume, typically expressed in kg/m³ or g/L. Unlike liquids and solids, gas density varies significantly with temperature and pressure changes.
Gas density is highly variable and depends on temperature and pressure, while liquid and solid densities are relatively constant. Gases are compressible and their molecules are far apart, making their density much lower than liquids or solids.
The ideal gas law can be rearranged to calculate density: ρ = PM/(ZRT), where P is pressure, M is molecular weight, Z is compressibility factor, R is the gas constant, and T is temperature.
Natural gas (mainly methane) has a density of about 0.7 kg/m³ at standard conditions, making it lighter than air (1.2 kg/m³). This is why natural gas leaks rise upward.
The compressibility factor Z accounts for real gas behavior deviating from ideal gas law. For most gases at moderate pressures and temperatures, Z ≈ 1. At high pressures or low temperatures, Z can differ significantly from 1.
Gas density is inversely proportional to temperature. As temperature increases, gas molecules move faster and occupy more space, decreasing density. Conversely, cooling a gas increases its density.
Gas density is commonly expressed in kg/m³ (SI units), g/L, or lb/ft³. The choice depends on the application and regional preferences. 1 kg/m³ equals 1 g/L.