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.
