# Question Video: Describing the Direction of Diffusion of Gas Particles in a Container Physics

Two gases are mixed together in the same container. In which direction would the particles of the gas shown in orange diffuse?

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### Video Transcript

Two gases are mixed together in the same container. In which direction would the particles of the gas shown in orange diffuse? (A) Toward the left. (B) Toward the right. (C) In all directions. Or (D) they would not diffuse.

To begin, let’s recall that diffusion refers to the process of particles spreading out evenly over a volume. To see what we mean, imagine we introduce gas particles to the left end of a container. Initially, the particles will be all bunched together at the left, but as time passes, they’ll collide and tend to move toward the right, spreading out until they’re evenly distributed. This is diffusion.

We should recall that particles move around like this by means of Brownian motion, which is the apparently random movement of many identical fluid particles due to repeated collisions.

Now if we look at the diagram given, we can see that all the particles, including the orange ones, are evenly distributed throughout the container. They’re not especially concentrated at either end, so they won’t diffuse toward either the right or left. Thus, we can eliminate answer options (A) and (B). Of course, the particles will still be moving around, but don’t be fooled by answer option (C). The orange particles will likely be moving in all directions because of Brownian motion, but this question is asking about the direction in which they’ll diffuse.

Since all the particles are already spread throughout the container, it seems that the gases have already gone through diffusion and cannot diffuse any further. Thus, we eliminate option (C). And we know that option (D) is the best answer. The particles of the gas shown in orange would not diffuse.