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Thread: Volume of Carbonated Water

  1. #1 Volume of Carbonated Water 
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    Ten hours of College Chem., and I cannot answer this with any theoretical "fit"!

    Does the overall liquid volume of carbonated water change measurably as the CO2 gas leaves solution? If it does, opening a bottle of soda, noting it's liquid level, then allowing it to lose it's carbonation, should reveal a lowered liquid level in the bottle, however small. It does NOT change, you say (perhaps)?

    Draw a bit of soda into an eyedropper, then watch as the liquid quantity amazingly decreases as the dissolved gas rises up in the area of the tube above the liquid!

    Try it! jocular


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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by jocular View Post
    Draw a bit of soda into an eyedropper, then watch as the liquid quantity amazingly decreases as the dissolved gas rises up in the area of the tube above the liquid!
    Surely, it is changing the volume of the liquid in the dropper by releasing gas and forcing the liquid out?


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  4. #3  
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    Here's the best answer I found by googling. The carbonated water itself is actually denser, but there are a lot of bubbles in it.
    atoms - Is a given volume of sparkling water lighter or heavier than the same volume of still water? - Physics Stack Exchange
    As a general rule, the volume of dissolved solutes in water is less than the volume an equal mass of the solutes will occupy as a solid, this is just because water molecules fill up space so badly, nearly anything can partially fit in interstitials. Since dry ice is already 50% heavier than water, CO2 solution is heavier than water, by unit liquid volume.
    But as you say, there is an out-of-equilibrium outgassing process--- you produce gas which is much lighter than the water or the CO2. If you weigh soda water which is out of equilibrium with an equal apparent volume of water (fill up the glass to the same height, ignoring the volume lost to bubbles), the water can be heavier than the soda-water, just because there is more liquid volume in the water.
    To see that there is a limit where this is true, consider filling up a beer glass 50% with Guiness, and compare with a full beer glass of water. The same holds for very fizzy drinks that can sustain a good volume of bubbles. For ordinary soda, the volume of bubbles trapped inside depend on the surface property of the glass, and the answer depends sensitively on whether the total gas volume contained in bubbles inside the soda is at a certain time greater than the total extra mass of dissolved CO2 in the bulk liquid. This depends on the precise configuration in a complicated way.

    Related to this is the phenomenon of dynamic shrink and swell in boiler level control. When you increase the load on a boiler or steam generator by drawing off more steam, the mass of water decreases. However, a whole lot of steam bubbles form which causes the level to rise. This creates some problems with level control systems.
    http://www.controlguru.com/wp/p48.html
    Last edited by Harold14370; May 28th, 2013 at 04:59 AM.
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  5. #4  
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by jocular View Post
    Draw a bit of soda into an eyedropper, then watch as the liquid quantity amazingly decreases as the dissolved gas rises up in the area of the tube above the liquid!
    Surely, it is changing the volume of the liquid in the dropper by releasing gas and forcing the liquid out?
    No, because two observations prevail: First, the liquid remains in the dropper; it is not forced out. Second, the pressure within the "system" of dissolved gas in water is basically constant: as the gas leaves the liquid and expands into the vacant space in the dropper, the pressure within the liquid is decreasing. Remember, the entire volume of the dropper was essentially evacuated upon pinching the bulb; thus, atmospheric pressure in the dropper tube was not present.

    It's an interesting little experiment, and I'm not at all certain my analysis of it is adequate at all! jocular
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  6. #5  
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    Quote Originally Posted by jocular View Post
    Quote Originally Posted by Strange View Post
    Quote Originally Posted by jocular View Post
    Draw a bit of soda into an eyedropper, then watch as the liquid quantity amazingly decreases as the dissolved gas rises up in the area of the tube above the liquid!
    Surely, it is changing the volume of the liquid in the dropper by releasing gas and forcing the liquid out?
    No, because two observations prevail: First, the liquid remains in the dropper; it is not forced out. Second, the pressure within the "system" of dissolved gas in water is basically constant: as the gas leaves the liquid and expands into the vacant space in the dropper, the pressure within the liquid is decreasing. Remember, the entire volume of the dropper was essentially evacuated upon pinching the bulb; thus, atmospheric pressure in the dropper tube was not present.

    It's an interesting little experiment, and I'm not at all certain my analysis of it is adequate at all! jocular
    Edit: (By-pass original post by using "quote" option, to ensure readership sees edit as added.....). Rethinking, my opinion of the rubber bulb evacuating the eyedropper of air by being squeezed is only half-correct: the glass tube contains atmospheric pressure while bulb is depressed, thus all air is not excluded during "sucking-up"........perhaps going on to something more interesting would appeal right now!
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