Intensive Properties

[305385703]

If density is an intensive property and does not rely on the amount of substance, why does the density of gas change as its amount changes?

[Brian Tangsombatvisit 1C]

The density of a gas remains the same even if the amount of gas changes.

Density is mass/volume. If you take some amount of gas away, you decrease the mass and volume of the gas by such an amount so that if you divide the new mass and volume, you get the same density.

[Brian_Ho_2B]

Density of a gas changes as its amount changes because unlike solids or liquids, gasses' volume is not fixed. Gasses can spread as much as they want so long as there is more space to spread to (entropy). Although it is possible to calculate the mass of a gas (eg. putting it in a balloon and measuring the full balloon's mass vs. an empty balloon's mass), finding the volume is a very difficult task. Density is an intensive property that doesn't depend on the volume of homogenous liquids and solids, but gases are never fixed as a certain volume.

[Adam Kramer 1A]

The density is mass/volume. Gas is unique because it does not have a fixed volume. The density of gas can change if you change the amount of gas but keep the volume of the container the same. If you add more gas to a container of a fixed volume, it will increase the density, for example.