How much fizz is inside a bottle of Coke?

It bubbles out to the surface uncontrollably at first, slowing down as the bottle sits in your fridge. Occasionally it dies completely, revealing a thick sweet cousin of your favorite drink.

On the suggestion of TiVo software engineer Steve Lacy, we decided to find out just how much gas is inside a 2-liter bottle of Coca-Cola.

I went down and bought a bottle of Coke at my corner drugstore, and for comparison I bought a cheap bottle of Andre champagne.  The plan was to affix a plastic bag to the coke bottle and shake as much gas loose as we could.

I started by rubber-banding a one-gallon plastic bag onto the bottle. This activity would best be described as "fumbling".
When we opened it, a gush of gas came out, but the coke sloshed back into the bottle. I gingerly shook the bottle until the plastic bag was totally full.  It took about 5 minutes. 

There are two ways to get gas "out of solution" as the chemists say.  One is to heat it up, and the other is to shake it.

We took the shaking route.

I don't understand exactly why shaking works, but it does. It works very well.

Everyone agreed that Brooke was the best at it. Now Brooke is looking for a career as a spokes-shaker.

There was a fair amount of soda sloshing in and out of the bag, but it was a closed system, so we captured all of the gas coming off of the Coke.

With the first bag full, I had to re-attach the cap and swap out a new, empty bag.

I thought the bag would go on a lot easier if the CO2 was excited, but I guess I was thinking of something else.

While the coke was fizzing away, we attached a 13-gallon garbage bag to the champange bottle. I was sure there was quite a bit more gas in this bottle than in the coke.
Apparently I shouldn't have shaken the champagne, because the force of the cork popping ripped right through the bag! The champagne gas collection was ruined.
Thankfully the champagne was cold, so we poured ourselves some glasses.

We only had three champagne flutes, so Stephanie had to drink out of the plastic bag. 

We toasted this, the 20th episode of "How much is Inside"!

Back to the Coke, we got the second bag attached and started shaking out more gas.
The second bag wasn't filling as quickly, we could all tell it was nearly flat.
Eventually the soda stopped fizzing, and we could tell it was finally flat. I detached the second bag.. it seemed like it had about 2 and a half liters of gas inside.
The first bag had about 2 liters inside too.  Although it was called a "gallon" bag, it obviously wasn't holding that much CO2 gas.

In this photo I am comparing it to an empty 2-liter bottle.

Here is the second bag stuffed inside a 2-liter shell.  It appears to also be holding a bit more than 2 liters of gas.

While I was calculating the total volume, Stephanie was calculating the street value of this pharmacy-grade coke gas!

To measure the volume of the gas in the bags, we submerged them in a shallow sink, marking where the water level started and ended.  The coke gas bags displaced about 4 and a half liters of volume! There was more than twice the amount of liquid!

I was a bit surprised, so I double-checked my results online.  Indeed, a search on Google revealed an extremely cool site called with the answer to this very same question.

It seems that the bubbles in such drinks do not simply provide fizz, but change the flavor of the drink as well. The Pop scientists call it "mouthfeel".

There was no room in my fridge for that flat bottle of Coca-Cola, so I brought it right back to the store for someone else to enjoy! 

Who knows, maybe they will like it better than regular Coke!

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Last updated March 4, 2002.

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