[Smokin' Joe]

Try this: Open a bottle of your favorite carbonated beverage. Secure a deflated balloon on top, over the open bottle. Allow the beverage to come to room temperature, or shake the bottle, getting the dissolved CO2 to come out of solution as a gas. You will find that a lot of CO2 can be dissolved in or removed from the liquid without noticeably affecting the volume of liquid.

Similarly, you can dissolve a half pint of sugar in a gallon of water, but you won't have a gallon and a half pint of liquid. Volumes are not additive, but the weights are.

[mountainlion]

Oil and refrigerant will almost make an additive volume as they are the same molecular weight but the pressure stays the same. CO2 is compressed to dissolve into the soda.

It would be neat if they put some catalysts into the CO2 so they could make more oil. There was a guy making fuel out of garbage by heating it and boosting the pressure to over 600 pounds. They could make fuel right in the ground.