Both sites say, in very similar words, that the way to calculate the density of water with 1% carbonation (by molecular concentration, it seems) is to take the weighted average:
0.99*density of water +0.01*density of CO2
They get that dissolved CO2
reduces the density by almost 1%, since the density of CO2
gas is very low compared to water at atmospheric pressure.
It's a comical example of two bad habits:
1. copying other web sites thoughtlessly.
2. using formulas thoughtlessly.
They aren't even remotely close to getting the description right. The dissolved CO2
isn't there as a bunch of little pockets of CO2
gas. It's there as individual molecules and ions (some ionizes). Since CO2
has a molecular weight about 2.5 times as big as H2
O, but doesn't occupy all that much more space, it actually raises the density, rather than lowering it. From looking up the experimentally observed partial molar volume of CO2
in water, I get that instead of the density going down almost 1% for every 1% carbonation, it actually goes up about 0.37%.
(published on 04/15/11)