# Equilibrium in a closed pop bottle

1. Dec 4, 2007

### pinkyjoshi65

Why is a sealed pop bottle said to be in a state of equilibrium, while an opened bottle is not?

2. Dec 4, 2007

### ozymandias

This is a bit of a semantic problem.

Thermodynamically, a system can only be in equilibrium with another system (this is, in fact, used to define temperature, the basic variable in thermodynamics).
Mechanically, a system is in equilibrium if the function that describes it does not change with time.
There is also chemical equilibrium and a host of other interpretations - I'm sure other disciplines have their own definitions of "equilibrium" as well. I'm not sure which meaning your usage carries, so I can't really give you a full answer.

My guess is that by "equilibrium" the statement refers to "stationary", i.e., a system whose variables do not change in time appreciably. If that is the case, the closed bottle's properties (temperature, e.g.) are much less affected by the external surroundings compared to the open bottle and are therefore "constant to a degree".

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Assaf
http://www.physicallyincorrect.com/" [Broken]

Last edited by a moderator: May 3, 2017
3. Dec 4, 2007

### chemisttree

Do you observe any changes to the contents of a closed pop bottle? How about the contents of an open one?

4. Dec 4, 2007

### chemisttree

I think pinky's question refers to the equilibrium of dissolved CO2 in the system.

5. Dec 4, 2007

### ozymandias

Arrrgh, after typing so much :rofl:.

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Assaf
http://www.physicallyincorrect.com/" [Broken]

Last edited by a moderator: May 3, 2017
6. Dec 4, 2007

### pinkyjoshi65

um..so in a sealed pop bottle, what happens to the dissolved co2? it definately stays in..any idea?

7. Dec 4, 2007

### Gokul43201

Staff Emeritus

What do you know about Henry's Law?

8. Dec 5, 2007

### pinkyjoshi65

this is a grade 12 question. I have not studied about Henry's Law..This has to do with the elements inside the bottle im guessing. If a closed bottle is at equi, then the components keep on forming again and again.

9. Dec 5, 2007

### chemisttree

Describe what happens when you open a bottle of pop. BTW, we call that 'soda' down here in Texas.

10. Dec 5, 2007

### pinkyjoshi65

when a soda bottle is opened, Co2 rushes out..

11. Dec 5, 2007

### chemisttree

After the initial pressure is released, what happens? Does this seem like it is in equilibrium?