Gas Density Calculator from Molecular Weight
To calculate gas density from molecular weight, we can use the ideal gas law equation rearranged to solve for density. Here's a comprehensive explanation and table showing gas densities for common gases:
Gas Density Calculation
The formula to calculate gas density from molecular weight is:ρ=PMRTρ=RTPMWhere:
- ρ (rho) is the gas density in kg/m³
- P is pressure in Pa (pascals)
- M is molecular weight in kg/mol
- R is the universal gas constant (8.314 J/(mol·K))
- T is temperature in K (kelvin)
Density Table for Common Gases
Here's a table showing the calculated densities for some common gases at standard temperature and pressure (101,325 Pa, 298.15 K):
| Gas | Molecular Weight (g/mol) | Density (kg/m³) |
|---|---|---|
| Nitrogen (N₂) | 28.02 | 1.145 |
| Oxygen (O₂) | 32.00 | 1.308 |
| Carbon Dioxide (CO₂) | 44.01 | 1.799 |
| Methane (CH₄) | 16.04 | 0.656 |
| Hydrogen (H₂) | 2.02 | 0.083 |
| Ammonia (NH₃) | 17.03 | 0.696 |
Key Points
- The density of a gas depends on its molecular weight, as well as the temperature and pressure.
- Gases with higher molecular weights generally have higher densities under the same conditions.
- Increasing pressure increases gas density, while increasing temperature decreases gas density2.
- This calculation assumes ideal gas behavior, which is generally accurate for most gases at standard conditions1.
- For more precise calculations, especially at high pressures or low temperatures, you may need to use a compressibility factor to account for non-ideal behavior5.
Remember that while this table provides a good reference, gas densities can vary significantly under different temperature and pressure conditions. Always consider the specific conditions when calculating or using gas densities in practical applications.