Ideal Gas Density Calculator
Calculate gas density: rho = PM/(RT). Enter pressure, molar mass, and temperature.
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Enter the gas pressure in atm, the molar mass of the gas in g/mol, and the temperature in Kelvin. The calculator applies rho = PM/(RT) with R = 0.08206 L atm/(mol K).
About the Ideal Gas Density Calculator
The ideal gas density equation rho = PM/(RT) is derived directly from the ideal gas law PV = nRT. It shows that gas density depends on pressure (directly), molar mass (directly), and temperature (inversely). This relationship is fundamental to atmospheric science, chemical engineering, and gas analysis.
Frequently Asked Questions
What is the density of air at standard conditions?
At 1 atm and 298 K (25 C), dry air (average molar mass 28.97 g/mol) has a density of about 1.18 g/L. At STP (273.15 K), it is about 1.29 g/L.
How does temperature affect gas density?
Gas density decreases as temperature increases (inverse relationship). This is why hot air rises: it is less dense than cooler surrounding air. Doubling absolute temperature halves the density at constant pressure.
When does this formula fail?
The ideal gas law (and this density formula) fails at high pressures and low temperatures, where gas molecules interact significantly. For real gases under these conditions, use the van der Waals equation or compressibility factor.