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Re: OT: Physical exitation of pressurised liquid gas.
by swampyankee (Parson) on Apr 11, 2009 at 02:36 UTC
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Shaking a liquid with gas dissolved in it will raise pressure (you can try this with soda). However, I think your question is not well-posed, as volatile means "1: readily vaporizable at a relatively low temperature" (see http://www.merriam-webster.com/dictionary/volatile), so "volatile gas" is an oxymoron. Almost invariably, a given mass of liquid will require less volume than the same mass of the same substance in gaseous phase, so condensation (the change in phase from gas to liquid) will tend to reduce pressure.
Information about American English usage here and here. Floating point issues? Please read this before posting. — emc
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so "volatile gas" is an oxymoron.
I said: "small amount of volatile gas under sufficient pressure to cause it to be liquid".
So, I guess I should have said "volatile liquid under sufficient pressure to prevent it from vaporising"?
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
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Re: OT: Physical exitation of pressurised liquid gas.
by Herkum (Parson) on Apr 11, 2009 at 14:27 UTC
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The shaking of the container is adding energy to the environment. Also the shaking makes it easier for the liquid to be more evenly distributed within the container and therefore become a gas.
How much of a change in pressure also depends on the contents and the amount of shaking. Quickly shake a soda bottle can make it explode when you open it. Vigorously shake a bottle of water for an hour, almost nothing happens.
The lighter you mentioned, I don't think it would be unreasonable that it would reach a more gaseous state for a little while after you shake it. With the liquid more distributed by the shaking, it would definitely make it easier for it to become a gas when you open the lighter rather than its normal state of being pooled at the bottom of the container.
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Re: OT: Physical exitation of pressurised liquid gas.
by atcroft (Abbot) on Apr 11, 2009 at 03:51 UTC
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My gut feeling is no, that it would not.
While shaking would likely add some energy to the system, I do not know if it would add enough to change the temperature (and thus the pressure) noticeably.
HTH.
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While shaking would likely add some energy to the system, I do not know if it would add enough to change the temperature (and thus the pressure) noticeably.
The liquid/gas: butane. The pressure vessel: a disposable lighter. As the fuel runs low, so the pressure inside drops until you reach the point where the flame is very feeble. Out of habit or instinct, I tend to shake it for a few seconds, and try again. Frequently, the flame is stronger afterward, I got to wondering if this effect was my imagination or real.
The likelihood is that any significant increase in pressure is due to the warming affect of my hand holding the lighter. But try as hard as I might to not grip the lighter whilst shaking it, so as not to cause it to be warmed by body heat. Still, shaking it does seem to produce a noticeable increase in pressure. Hence the question.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
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Re: OT: Physical exitation of pressurised liquid gas.
by Anonymous Monk on Apr 11, 2009 at 02:38 UTC
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Try it out :) Get a mason jar with one of those poptops, push the poptop, and listen to hear how loud it popsback | [reply] |
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The poptop only works if the pressure inside the jar is less than the atmospheric pressure. To liquify a gas will by definition need more than atmospheric pressure (unless you cool it way down, but that is cheating).
CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James
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Mason jars are use for home food preserves. Their lid are like those of juice bottles. They pop once the seal is broken to indicate a health breach.
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