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I buy a lot of carbonated water, its pretty much all I drink. There is something I've noticed that just made me curious though.

The usual brand I buy is the cheapest one available, 14 cents per 1,5l. This one almost always tries to give me a surprise shower when I open it, no matter how still I keep it prior to opening. The bubbles are large and plentiful at first but it goes flat pretty quickly, usually within the day but thats fine since I'll drink it in a day anyways.

The other brand I buy when the first one isn't available, its the second cheapest one and is 35 cents per 1.5l. Opens up pretty calmly, the bubbles are much smaller but lots of them around. The interesting bit is that it doesn't go flat nearly as quickly and I can expect some carbonation to be left even a few days later. Another point to make is that the second one behaves much more like various other brands.

The question is, what could cause such difference in the bubbling behavior?

The bottles are the same kind of clear plastic, the ingredients aren't listed which should mean that its just water + $\ce{CO2}$. Over here, if they put any other chemical in it, they are required to name it on the bottle, many water bottles have chlorine in them for example.

Could it be the carbonation process? Or the natural water composition? Maybe the transportation or storage?

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  • $\begingroup$ Are the dates of manufacture the same for the bottles you compared? $\endgroup$
    – N A
    Commented Feb 17, 2016 at 1:44
  • $\begingroup$ They don't have a manufacturing date but the "best before" date is similarly ~11-12 months from the date of purchase $\endgroup$
    – user81993
    Commented Feb 17, 2016 at 4:04
  • $\begingroup$ Most of the carbon dioxide is present as dissolved gas. I'd guess that the cheaper bottle that fizzes easily has a much higher concentration of particulates which become nucleation sites. $\endgroup$
    – MaxW
    Commented Feb 17, 2016 at 4:21

1 Answer 1

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Carbonated water is supersaturated in carbon dioxide, and the only thing preventing all that excess $\ce{CO2}$ from bursting out all at once is the lack of nucleation sites for $\ce{CO2}$ bubbles to form. These nucleation sites can be almost any solid (including the sides of the container to some degree) from undissolved salts to soil particles or tiny particles of most anything.

The most likely reason for the formation of such a copious amount of bubbles forming in the cheap water is the presence of a large amount of undissolved solids relative to the more expensive waters. Depending on the product, one step of the processing of carbonated water is filtering in order to make the product appear clearer and more sparkly (and maybe to prevent rapid formation of $\ce{CO2}$ bubbles). Of course this process costs money, and it is likely that the cheaper brand either skips the filtration process or uses a much less efficient (and cheaper) process.

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