[Polleke]

hallo all,

I have the following discussion going on: when putting a (full) bottle of coca cola in the freezer the bottle will break.

I was always convinced that the water in the cola is causing this. Because the volume goes up when freezing water.
Now someone told me it is moslty the CO2 in the cola that causes the breaking of the bottle.

Neither one of us is able to really give a good background on what is happening with the CO2 in the bottle, in the cola and the correct influence on the proces, the breaking of the bottle.

any suggestions?

[nj_bartel]

Gases increase solubility in liquids with decrease in temperature.  It's the freezing water.

[Loyal]

It would have to say it is the water as well.  If anything the pressure of the gas goes down with temperature and it also increases solubility.   So the force on the bottle is getting small from the gas.   Water on the other hand gains a significant amount of volume as it freezes.

[Polleke]

It would have to say it is the water as well.  If anything the pressure of the gas goes down with temperature and it also increases solubility.   So the force on the bottle is getting small from the gas.   Water on the other hand gains a significant amount of volume as it freezes.

Yeah, well that was my idea first, that it is the water and not the gas, however the person that spoke to me about the gas is a teacher in chemistry so I was a little bit wondered about it and dont really now what to respond because I am not a chemist.

[Rabn]

The answer is actually that the bottle breaks because of both the water and the gas.  As the soda freezes, it expands, eventually the frozen soda expands so much that the CO2 gas in the bottle is compressed to the point where the pressure exerted by the gas on the plastic bottle makes the bottle burst.  If the bottle breaks strictly due to the water expansion you would expect to see stretch marks in the plastic bottle around the areas where the bottle broke.  Normally a bottle splits fairly cleanly, indicating a sudden release of energy, the energy of the compressed CO2 gas. So it's both.

[Polleke]

The answer is actually that the bottle breaks because of both the water and the gas.  As the soda freezes, it expands, eventually the frozen soda expands so much that the CO2 gas in the bottle is compressed to the point where the pressure exerted by the gas on the plastic bottle makes the bottle burst.  If the bottle breaks strictly due to the water expansion you would expect to see stretch marks in the plastic bottle around the areas where the bottle broke.  Normally a bottle splits fairly cleanly, indicating a sudden release of energy, the energy of the compressed CO2 gas. So it's both.

Following your explenation, it means that the CO2 gas is no longer in the fluid ?
The CO2 is "in" the bottle, outside the cola when freezing? or?

It is because of the lowering of the temperature that the liquid cant hold the CO2 and releases the CO2 into the bottle? or?

[macman104]

I think what Rabn is saying is that the gas inside does become more soluble as the temperature decreases.  However, since water is one of those nifty things that expands when it freezes, the gas actually starts getting compressed into very small spaces in the bottle.  Eventually, the buildup of that compression results in extreme pressures that cause it to explode.  You can tell that because the glass cracks cleanly, indicating a quick fracture, and not a slow process like the ice stretching the glass till it breaks.

Now, the whole root cause of this is of course the fact that water expands as it freezes.  I wonder...if you had a glass bottle of an organic with CO₂ dissolved somehow, if it would shatter when you freeze it?  Actually, that sounds like it should be relatively easy to setup, right?

[nj_bartel]

It doesn't seem like it would.  If it did, there'd be something odd going on.

[Polleke]

I think what Rabn is saying is that the gas inside does become more soluble as the temperature decreases.  However, since water is one of those nifty things that expands when it freezes, the gas actually starts getting compressed into very small spaces in the bottle.  Eventually, the buildup of that compression results in extreme pressures that cause it to explode.  You can tell that because the glass cracks cleanly, indicating a quick fracture, and not a slow process like the ice stretching the glass till it breaks

The gas that is compressed into very small spaces in the bottle, you mean that the gas is outside the liquid or compressed in the liquid itself?
(the solubilaty is higher at lower temperatures. Expectations: more gas in the fluid beter solution, but you state it is compressed more because of expanding of the frozen water ==> the gas is outside the freezing water?)

[ARGOS++]

Dear Polleke;

Have you ever seen such frozen/broken bottles and cans?

I have seen them for a few winters, because we owned a food store.
If you keep in mind that the frozen coca or soda is still keeping the original shape of the can/bottle quite well, then you know that the freezing process has destroyed the container and that CO₂ is more or less only a spectator.

I hope it may help for a better understanding.
Good Luck!
                    ARGOS⁺⁺

[macman104]

The gas that is compressed into very small spaces in the bottle, you mean that the gas is outside the liquid or compressed in the liquid itself?
(the solubilaty is higher at lower temperatures. Expectations: more gas in the fluid beter solution, but you state it is compressed more because of expanding of the frozen water ==> the gas is outside the freezing water?)

I honestly don't know.  Rabn sounds like they're (she?) trying to say that the gas is compressed outside of the water, but I was just trying to reword it from what I understood Rabn to be saying.

[Polleke]

Dear Polleke;

Have you ever seen such frozen/broken bottles and cans?

I have seen them for a few winters, because we owned a food store.
If you keep in mind that the frozen coca or soda is still keeping the original shape of the can/bottle quite well, then you know that the freezing process has destroyed the container and that CO₂ is more or less only a spectator.

I hope it may help for a better understanding.
Good Luck!
                    ARGOS⁺⁺

Well that was also my idea or point of view.
The idea about the CO2 was raised by a chemistry teachter and thats why I got confused and wasnt able to completely understand it all.

So it is the water, coca itself that is causing the break and not the CO2



@macman104 

I see.

Well it still makes me wonder if the gas would leave the liquid or not.

anyway, intresting topic this cola problem.

[ARGOS++]

Dear Polleke;

Additional word about CO₂:
Specially in the clear frozen soda (mineral or fruits) you can see several bubbles different shapes with a diameter of ~0.5 till ~2 cm, indicating that during the freezing process a little CO₂ has been released; maybe according to the release of total pressure in the moment when the container starts to break.

Good Luck!
                    ARGOS⁺⁺

[Polleke]

another general question: the CO2 is located in the fluid normally , right?
Or is there a Chemical equilibrium between the CO2 in the liquid and CO2 outside the liquid (in the bottle), meaning there is also CO2 outside the liquid.

and:

Dear Polleke;

Additional word about CO₂:
Specially in the clear frozen soda (mineral or fruits) you can see several bubbles different shapes with a diameter of ~0.5 till ~2 cm, indicating that during the freezing process a little CO₂ has been released; maybe according to the release of total pressure in the moment when the container starts to break.

Good Luck!
                    ARGOS⁺⁺

the bubbles you are talking about, you do mean bubbles in the frozen soda?

If so: how do you know that those bubbles mean that CO2 escaped?
Cant those bubbles simply be the CO2 in the frozen liquid?

Maybe I should simply put a cola bottle with the CO2 still in it in my freezer and another one without the CO2

well, I never realised that a simple soda could cause so mucht problems haha


PS. I do not understand what you mean by: maybe according to the release of total pressure in the moment when the container starts to break.

Or do you mean that maybe a bit of the CO2 escapes at the moment when the total pressure in the bottle is "gone" because of the breaking of the bottle? (meaning that because the bottle breaks the CO2 in the bottle can simply escapes?)

[Loyal]

The answer is actually that the bottle breaks because of both the water and the gas.  As the soda freezes, it expands, eventually the frozen soda expands so much that the CO2 gas in the bottle is compressed to the point where the pressure exerted by the gas on the plastic bottle makes the bottle burst.  If the bottle breaks strictly due to the water expansion you would expect to see stretch marks in the plastic bottle around the areas where the bottle broke.  Normally a bottle splits fairly cleanly, indicating a sudden release of energy, the energy of the compressed CO2 gas. So it's both.

Except that is still a function of the water acting on the gas.  The gas wouldn't do it on its own.