Question

The particles in the oxygen gas animation show many different kinds of motions. Identify three different kinds of motions/interactions you observe. Which motions create pressure on the walls of the container?

Answer 1

Well I can't see the animation, but what I can tell you is that O2 gas in a container would have Van der Waals forces (London Dispersion forces). Ideally, gases have perfect collision, they bounce against each other perfectly. Gases move in all directions, bouncing on everything they touch. Since the container is holding the gas inside, the gas would bounce on the walls of the container. The smaller the container, the more densely packed the O2 molecules are and the more pressure is present in the container. The bigger the container, the less densely packed and the lesser the pressure.

In a large vs. small container, a larger container would have the higher entropy (disorder/chaos) for the O2 gas.

Answer 2

States
of Matter interactive. (Source: PhET Interactive Simu-
lations, University of Colorado, http://phet.colorado.edu)

If you want to watch the animation

Answer 3

Well, watch what the molecules are doing, and tell 3 things about it.

What causes pressure to increase?

Answer 4

the molecules spin, move side to side, and up and down?

Answer 5

Sure, why not? As long as you say something consistent with the simulation, you can't be wrong.

What causes pressure to increase?

Answer 6

I just thought there would be more of a scientific way of saying that...

I am really not super sure what causes pressure to increase... I am trying t think of a can of soda and when you shake it, the molecules are moving faster and without release pressure would build up

Answer 7

Well, the question isn't really asked in a technical-scientific way, but all you need to know about the motion of gases are that they are completely random, move in all directions, and have a negligible energy loss in collision that we can safely assume they have "perfect collision".

As for the soda can example, I can give you a more scientific answer. The Carbon Dioxide (CO2) gas molecules will likely form a temporary ionic attraction to the other components of soda (like the syrup, flavoring, sugar, etc) when you shake it rapidly. Friction in the can against other molecules and the wall of the inside will also increase the temperature of the can slightly. As the heat energy of the can increases (enthalpy), the entropy (disorder) increases. The entropy also increases due to the complexity you introduce to the molecules inside the can. As a result, pressure builds up and the force within the can is greater than the normal force of the inside of the can, and would cause the can to burst.

Answer 8

So the answer to which motions create pressure on the walls would be with the increase of heat, the molecules move faster bumping against each other and the walls containers repeatedly?

Answer 9

That would be an okay answer in my book. If they specifically wanted motion you could rephrase it by saying that it bounces against the wall of the container randomly (increasing the pressure) and then give more explanation.

Answer 10

I will take your advice and thank you for putting it in a better perspective.

Answer 11

You're welcome :)