Oxygen Gas Density at STP Calculator

Calculator

STP definition

Pressure

Pressure unit

Temperature

Temperature unit

Molar mass of oxygen Use 31.998 g/mol for O2.

Compressibility factor Z

Significant figures

Gas constant used

Formula Used

The calculator uses the ideal gas density equation with an optional real gas correction.

ρ = (P × M) / (Z × R × T)

Here, ρ is density in g/L. P is absolute pressure in atm. M is molar mass in g/mol. Z is the compressibility factor. R is 0.082057366 L atm mol^-1 K^-1. T is absolute temperature in kelvin.

How to Use This Calculator

Select the STP definition required by your class or lab.
Choose custom conditions when pressure or temperature differs.
Keep molar mass at 31.998 g/mol for ordinary oxygen gas.
Use Z = 1 for ideal gas work.
Enter a given Z value for real gas correction.
Press Calculate to show the result above the form.
Use CSV or PDF buttons to save the same calculation.

Example Data Table

Case	Pressure	Temperature	Z	O2 Density
Traditional STP	1 atm	273.15 K	1	1.429 g/L
IUPAC STP	1 bar	273.15 K	1	1.410 g/L
Room condition	1 atm	298.15 K	1	1.308 g/L

Oxygen Density at STP

Oxygen is a diatomic gas under ordinary laboratory conditions. Its formula is O2, so its molar mass is near 31.998 grams per mole. Density at STP is a classic chemistry value because it links mass, volume, pressure, and temperature in one simple result. The calculator uses the ideal gas law, then adjusts it with a compressibility factor when needed.

Why STP Matters

STP gives a shared reference point. Many textbooks use 0 degrees Celsius and 1 atmosphere. Some modern references use 0 degrees Celsius and 1 bar. That small pressure change changes the final density. This page lets you switch standards, so your answer matches your source. For dry oxygen at 0 degrees Celsius and 1 atmosphere, the ideal result is about 1.429 grams per liter.

Useful Inputs

Pressure raises density because more gas particles occupy the same volume. Temperature lowers density because warmer gas expands. Molar mass also matters. Oxygen is heavier than nitrogen, so oxygen gas is denser than air under similar conditions. Compressibility factor Z is normally close to 1 at STP. Use Z below 1 or above 1 only when your data source gives a real gas correction.

Reading the Result

The main result is shown in grams per liter. The same number is also kilograms per cubic meter, because those units are equivalent for gas density. Extra outputs include pounds per cubic foot, molar volume, and moles per liter. These values help with lab reports, gas storage checks, and stoichiometry problems.

Good Practice

Use consistent units before comparing answers. State which STP definition you used. Round final results to the required significant figures. Keep more digits during calculation, especially when pressure is entered in kilopascals or millimeters of mercury. If your assignment assumes ideal behavior, leave Z at 1. If it asks for real gas behavior, enter the given Z value. This makes the calculation transparent and easy to verify.

Common Uses

Students use oxygen density to check molar volume, gas collection data, and cylinder estimates. Teachers use it to show how one formula connects many gas properties. Technicians can compare dry gas estimates before using detailed safety standards. Always follow your official lab method carefully for final values.

FAQs

What is the density of oxygen gas at STP?

Using 0 degrees Celsius, 1 atmosphere, and ideal behavior, oxygen gas has a density of about 1.429 g/L.

Which molar mass should I use for oxygen gas?

Use 31.998 g/mol for O2. Oxygen gas is diatomic, so one molecule contains two oxygen atoms.

Why does STP definition change the answer?

Traditional STP uses 1 atmosphere. IUPAC STP uses 1 bar. Since 1 bar is slightly lower, the density is slightly lower.

Should I set Z to 1?

Yes, set Z to 1 for ideal gas calculations. Change it only when a real gas compressibility factor is supplied.

Why is density shown in kg/m³ too?

For gases, 1 g/L equals 1 kg/m³. Both units show the same numeric value with different unit labels.

Can I use this for other gases?

Yes. Enter the other gas molar mass. The formula works for ideal gas density under any valid gas condition.

Why must temperature be in kelvin?

Gas law equations require absolute temperature. The calculator converts Celsius and Fahrenheit to kelvin before solving.

What happens if pressure increases?

Density increases in direct proportion to pressure when temperature, molar mass, and Z remain unchanged.