Gas Density Calculator
Density of an ideal gas.
Formula first
Overview
The gas density equation expresses the mass per unit volume of an ideal gas as a function of its pressure, molar mass, and temperature. It is derived from the Ideal Gas Law by substituting the relationship between moles, mass, and molar mass into the standard PV=nRT formula.
Symbols
Variables
\rho = Density, P = Pressure, M = Molar Mass, R = Gas Constant, T = Temperature
Apply it well
When To Use
When to use: This formula is applicable when determining the density of a gas under specific environmental conditions or when identifying an unknown gas using its measured density. It assumes the gas behaves ideally, which is most accurate at high temperatures and low pressures.
Why it matters: Calculating gas density is essential for predicting the buoyancy of balloons, understanding atmospheric layering, and assessing the safety of industrial gas leaks. In chemical engineering, it allows for the precise calculation of mass flow rates within piping systems.
Avoid these traps
Common Mistakes
- Using Celsius instead of Kelvin.
- Mismatching R units with P units.
One free problem
Practice Problem
Calculate the density of oxygen gas (O₂) at a pressure of 2.00 atm and a temperature of 300 K. Use a molar mass of 32.00 g/mol and R = 0.0821 L·atm/mol·K.
Solve for:
Hint: Plug the values directly into the density formula: d = (P × M) / (R × T).
The full worked solution stays in the interactive walkthrough.
References
Sources
- Atkins' Physical Chemistry (11th ed.)
- Halliday, Resnick, Walker, Fundamentals of Physics (11th ed.)
- Wikipedia: Ideal gas law
- NIST CODATA
- IUPAC Gold Book
- Atkins' Physical Chemistry
- NIST Chemistry WebBook
- Wikipedia: Ideal gas