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Offline Winga

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A Special Question!
« on: February 20, 2005, 06:13:29 AM »
Experiment 1:
In a room, there is a glass milk bottle, then, put a piece of burning paper into it and cover the mouth with a boiled egg. Finally, the egg will suck into the bottle.

How can we explain it by using ideal gas law? (or other laws)

Experiment 2:
If we want to remove the egg from the bottle in experiment 1 by using the following method:
Use a new glass milk bottle, put a piece of burning paper into it, invert the previous egg contained bottle and connect its mouth to the new bottle's mouth.

Assume there is no gap between the mouths, can the egg go down to another bottle? How to explain it by using ideal gas law? (or other laws)

Another question is that, in exp.2, is the no. of gas molecules inside the bottle enough to push the egg out?
« Last Edit: February 20, 2005, 11:49:54 AM by Winga »

Offline Mitch

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Re:A Special Question!
« Reply #1 on: February 20, 2005, 11:25:01 AM »
1.) You create a vacuum in the milk bottle.
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Offline Winga

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Re:A Special Question!
« Reply #2 on: February 20, 2005, 12:04:17 PM »
It is not vacuum. Carbon dioxide will generate when the paper is being burnt.
(Will water vapour also generate from burning a piece of paper?)

I have found an answer from other websites.
When we burn the paper, the pressure inside the bottle increase (the gases expand), when oxygen is consumed, the gases cool down and contract (partial vacuum). The pressure inside the bottle decreases, the greater pressure outside the bottle will force the egg into it.

There is another method to get the egg out of the bottle, besides exp.2.

I really want to know that the pressure inside the bottle (exp.2, egg contained) is same as the atmosphere's (exp.1, the room), does the atmosphere pressure generate a greater force than that of the bottle's?

Offline Mitch

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Re:A Special Question!
« Reply #3 on: February 20, 2005, 12:10:37 PM »
but is it a 1:1 mole ratio?   :tomaatit:
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Offline Winga

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Re:A Special Question!
« Reply #4 on: February 20, 2005, 03:49:40 PM »
1 mole of gas molecule occupy a certain volume at standard temperature.
2 moles of gas molecule occupy a double volume in same conditions.

So, the ratio is 1:1.

If the container just fit with the egg at all, there will only a small amount of gas molecules inside this conatiner. Although its pressure is the same as outside, just a few molcules can force the egg out?

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Re:A Special Question!
« Reply #5 on: February 20, 2005, 07:43:40 PM »
The pressue, not the number of molecules determines whether the egg gets out.

Pressure is a result of collisions of molecules with an object. In a smaller volume with fewer molecules, the rate of collisions  is the same if the pressure is the same. The smaller distances to collision offsets  the lack in numbers.

Offline Mitch

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Re:A Special Question!
« Reply #6 on: February 20, 2005, 09:31:40 PM »
Well, I thought of it as if you have O2, a certain amount of CO2 and H2O would be given off. Perhaps its not a 1:1 mole ratio since some of the oxygen is shared with the H2O
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Offline Winga

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Re:A Special Question!
« Reply #7 on: February 21, 2005, 09:34:58 AM »
The pressue, not the number of molecules determines whether the egg gets out.

Pressure is a result of collisions of molecules with an object. In a smaller volume with fewer molecules, the rate of collisions  is the same if the pressure is the same. The smaller distances to collision offsets  the lack in numbers.
The force generated by a few molecules may not enough to against the resistance between and the egg and the bottle nexk, right?

Just consider there are only 10 molecules of gas in the bottle containing an egg, while the outside is vacuum, will the egg get out?

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Re:A Special Question!
« Reply #8 on: February 21, 2005, 12:58:12 PM »
As a practical matter, 10 molecules represent virtually no space between the egg and container.

 Even with a microscopic space, the 10 molecules can be at atmospheric pressure and can only  begin to push the egg out into the vacuum assuming atmospheric pressure is sufficient to overcome resistance at the neck.
The problem is as the egg begins to be pushed out, much more space relative to the starting point is created resulting in a huge percent  decrease in frequency of collisions and pressure which the few molecules will not overcome.

« Last Edit: February 21, 2005, 01:33:07 PM by Demotivator »

Offline Winga

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Re:A Special Question!
« Reply #9 on: February 21, 2005, 10:21:07 PM »
Therefore, the 10 molecules still can push the egg but they take long long time, right? (or they can't?)

Demotivator

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Re:A Special Question!
« Reply #10 on: February 21, 2005, 10:56:10 PM »
They won't be be able to push the egg out since the friction at the neck is too great for the extremely small pressure that remains in the expanded space.
However, if you assume an ideal frictionless scenario, then it can push the egg out into a perfect vacuum after a very long time.

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