Why do gases mix completely over time due to diffusion?

Gases mix completely over time due to diffusion because of the random, continuous motion of their particles.

Diffusion is a process that involves the movement of particles from an area of high concentration to an area of low concentration. In the case of gases, the particles are in constant, random motion and have a lot of space between them. This allows them to move freely and mix with other gas particles.

The process of diffusion in gases is driven by the kinetic energy of the particles. This kinetic energy is a result of the temperature of the gas. The higher the temperature, the faster the particles move and the quicker the diffusion occurs. This is why you might notice that a smell, such as cooking food or perfume, spreads faster in a warm room than in a cold one.

Another factor that affects the rate of diffusion is the size of the particles. Lighter particles move faster and diffuse more quickly than heavier ones. For example, helium gas (which has very light particles) will diffuse faster than a heavier gas like carbon dioxide.

In summary, gases mix completely over time due to diffusion because their particles are in constant, random motion. This motion, combined with the large spaces between particles in a gas, allows them to spread out and mix until they are evenly distributed. The rate of this diffusion is affected by factors such as temperature and the size of the particles.