Yes, pure oxygen is slightly heavier than air.
Understanding the Density Difference
Pure oxygen is approximately 1.1 times heavier than air. This means that a given volume of pure oxygen has 1.1 times the mass of the same volume of air. This difference arises from the composition of air. Air is a mixture of gases, primarily nitrogen (approximately 78%) and oxygen (approximately 21%), along with smaller amounts of other gases like argon, carbon dioxide, and water vapor. While oxygen is heavier than nitrogen, the presence of lighter gases like nitrogen in air lowers the overall density.
Several sources confirm this fact:
- Britannica: "Pure oxygen is 1.1 times heavier than air."
- Various Online Sources: Multiple reputable online sources, including those cited in the references, support the assertion that pure oxygen is denser than air.
Why Gases Don't Always Settle According to Density
While oxygen is heavier than air, it doesn't simply sink to the bottom of the atmosphere. This is due to several factors:
- Air Mixing: The atmosphere is constantly in motion due to wind, convection currents, and other meteorological phenomena. This mixing prevents heavier gases from completely settling out.
- Molecular Motion: Gas molecules are constantly moving and colliding, leading to a degree of random distribution, despite density differences.
Examples of other heavier-than-air gases that don't settle completely to the ground include carbon dioxide. As noted in some of the provided resources, carbon dioxide is indeed heavier than air, yet it doesn't accumulate at ground level due to the mixing effects mentioned above.
