Gases mix evenly
Most gas mixtures are homogeneous.
A wall removed
A box has hydrogen on the left and oxygen on the right, separated by a wall. The wall is removed.
What will the gases do?
What this lesson covers
The idea
Gas particles move freely in all directions and mix uniformly with other gases, so most mixtures of gases are homogeneous; smoke, fog and dust in air are heterogeneous mixtures with a gas as one component.
A wall removed
A box has hydrogen on the left and oxygen on the right, separated by a wall. The wall is removed.
What will the gases do?
- Mix evenly through the whole box
- Stay in their own halves
- Sink to the bottom
Remove the partition
Slide the seconds. Then look at air with smoke and air with fog.
Gas mixtures
Gas particles are free to move in all directions, so they mix easily and uniformly with other gases. Hence most mixtures of gases are homogeneous, such as hydrogen and oxygen (used as a rocket fuel).
Exceptions. Smoke (solid particles suspended in air), fog (tiny liquid water droplets in air) and dust in the air are heterogeneous mixtures with a gas as one of the components.
Notes
Gas particles move freely and mix uniformly, so most gas mixtures are homogeneous. Smoke, fog and dust in air are heterogeneous.
Check yourself
Why do two gases mix uniformly?
A mixture of hydrogen and oxygen gases is…
Smoke is…
- Their particles are packed tightly and cannot move. Gas particles are far apart and free.
- They always form layers. Gases mix evenly.
- Their particles move freely in all directions — correct. Yes.
- homogeneous — correct. Yes.
- heterogeneous. It is uniform.
- a suspension. Not a suspension.
- two gases mixed uniformly. Smoke has solid particles.
- solid particles suspended in air, a heterogeneous mixture — correct. Yes.
- a pure gas. Smoke is a mixture.