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Soonrboy
9/22/2007, 09:26 PM
the amount of fizz in pop and whether temperature effects the fizz. I know it has to do with carbon dioxide and air pressure, but just realized that I don't really know what happens when you open a bottle or can of pop and the fizz happens.

I told him it was magic already, but I really need to save some face. He's in seventh grade, and I dont want him to know more than I do. Yet.

Yes, I can research it, but I know someone on here can explain it better.

OCUDad
9/22/2007, 09:51 PM
You really need Ike for this, but I'll give it a try...

Things contract under high pressure and expand under low pressure. Things also contract when cold and expand when hot. In general, gases expand and contract faster than liquids, and liquids expand/contract faster than solids.

Carbonation is a gas (CO2) in a liquid, bottled or canned under high pressure. When the container is opened, the pressure is equalized with the surrounding air, meaning the pressure in the container drops. The gas expands and escapes from the liquid in the form of fizz. Similarly, if you heat the carbonated liquid, even more gas escapes because it expands faster than the liquid it's in. That's why if you heat soda or leave it out in the open for long, it goes flat - all the gas escapes through expansion.

Anyway, I think that's close.

Petro-Sooner
9/22/2007, 10:34 PM
Thats sounds about right. I dont think I could add much more. Other than talking about the chemisty, hence CO2, of the pop. Not sure if thats more than what a 7th grader would have to look into. Dads explaination reminds me of a can of air that is used to blow off computer key boards, sowing machines, etc... The can is under pressure and when you use it you will notice the can gets cool to the touch. Thats decompressional cooling at work. When you blow up a bike tire with a pump you can feel the connection piece warm. Compressional warming. Not sure that helps at all. I love science now. Not so much back then.

SoonerAtKU
9/23/2007, 07:22 AM
http://en.wikipedia.org/wiki/Boyle's_law

Soonrboy
9/27/2007, 09:42 PM
Okay, but if I pour fairly new pop from one cup into another, why is there more carbon dioxide released? The air pressure should be the same in the glasses shouldn't it?

GottaHavePride
9/27/2007, 09:46 PM
Agitation - the CO2 doesn't stay dissolved when you're stirring stuff about?

Soonrboy
9/27/2007, 09:51 PM
carbon dioxide is released from the soda to stabilize the air pressure and it is released when agitated?

I know that the pop is flat when all the co2 is released.

GottaHavePride
9/27/2007, 09:59 PM
I think I would describe it that CO2 is soluble in liquid, but it's unstable. In a pressurized container, the pressure above the liquid balances the CO2's tendency to escape the solution. When you open the container, removing the pressure, CO2 begins vaporizing out of the solution. Pouring the soda back and forth just accelerates the process by agitating the CO2.

Soonrboy
9/27/2007, 10:07 PM
vaporizing, realllllly?? Is that why if you leave a glass of soda out for a long time, it goes flat, even if you haven't agitated it, because the co2 has vaporized?

very interesting.

GottaHavePride
9/27/2007, 10:08 PM
Something like that. I may not be using quite the right terminology, but it's that sort of idea.

Soonrboy
9/27/2007, 10:10 PM
another question...2 liter dr. pepper releases co2 so quickly that it spills over, while others do not.

Is this because there is more co2 in dr. pepper 2 liter bottles than others?

Ike
9/27/2007, 10:41 PM
here's a good article about it. google can help you find others.

http://www.edwardwillett.com/Columns/fizzcool.htm

Some of the more interesting effects to come out of carbonated beverages:
a) CO2 lowers the freezing point of the beverage. So if you chill it to a few degrees below freezing, but not enough to actually freeze the stuff, and then pop the cap, the escaping gas will cause the freezing temp of the beverage to rise, instantly freezing the stuff right on top.

b) Because carbonated beverages are mostly water, there are some interesting effects that occur when you actually freeze the stuff while still in the bottle. These effects have to do with the fact that water expands when frozen, which gives the gas a smaller volume to reside in, and thus, increases the pressure of the contents. Opening a bottle or can of partially frozen soda indoors will give you cause for cleaning your ceiling.

Ike
9/27/2007, 10:50 PM
vaporizing, realllllly?? Is that why if you leave a glass of soda out for a long time, it goes flat, even if you haven't agitated it, because the co2 has vaporized?

very interesting.


When not under pressure, all of the CO2 will eventually escape from the liquid. Agitation helps speed up the process by giving the gas molecules places to collect and form bubbles.

SoonerAtKU
9/27/2007, 10:54 PM
Think of it this way...the CO2 is held inside the liquid, but doesn't want to be there. The only thing holding it in is pressure and, ideally, a colder temperature. If you decrease the pressure by opening it, raise the temp, agitate, or provide more surface area for the gas to escape, it's going to go flat faster. Therefore, if you want to keep it fizzier longer, keep it in the fridge, don't open it more than you have to, keep it upright, and for the luvva pete, don't shake it.

Soonrboy
9/28/2007, 07:54 AM
thanks everyone...

OUDoc
9/28/2007, 08:10 AM
You're welcome.

sooner_born_1960
9/28/2007, 08:13 AM
another question...2 liter dr. pepper releases co2 so quickly that it spills over, while others do not.

Is this because there is more co2 in dr. pepper 2 liter bottles than others?
I, too, have noticed that Dr. Pepper seems to be over carbonated. Does anyone have an explanation for this?