1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to get an egg into a bottle

  1. Aug 10, 2007 #1
    I have a quick question for you, how do you get an egg into a bottle?
    I am finishing my teaching training and am researching misconceptions in science.
    One that particularly interests me is reported differently in text books and web sites etc.

    Allow me to set the scene:

    1. Hard boiled egg - shell removed.
    2. Conical flask or glass bottle - neck narrower than egg.
    3. Boiling water or burning candle - to go into bottle.

    Could you please tell me your theories on how the egg is then 'sucked' into the bottle.
    Then you can give me you researched answer.
    But first I need your honest theory.

    Many Kind Regards
  2. jcsd
  3. Aug 10, 2007 #2
    candle uses oxgen creating a vacuum effect on the egg?
  4. Aug 10, 2007 #3
    x2, the egg creates a seal, the candle uses up the oxgen which creates a lower pressure, the higher pressure outside pushes on the egg.
  5. Aug 10, 2007 #4


    User Avatar
    Gold Member

    Using up the oxygen is not a viable answer. Think of what is happening to the air inside the flask and the function of the egg.
  6. Aug 10, 2007 #5


    User Avatar
    Science Advisor
    Homework Helper

    Burning oxygen create exactly as much CO2 as it used O2.
    It's amazing how often the burning candle sucking up water into a jar experiment is done to prove the amount of oxygen.
  7. Aug 10, 2007 #6
    Creation of Vacuum Is the Answer

    I've never put an egg into a bottle. If it works, it has to be by creation of a partial vacuum inside the bottle. The heat will drive out some of the air in the bottle either before the egg is placed upon it or else aftterward, if the egg-bottle seal allows one way air movement outward. Then when the air inside cools it will have less than atmospheric pressure, and whamo, the egg is pushed into the botlle by the pressurre diiference.
    Last edited: Aug 10, 2007
  8. Aug 10, 2007 #7


    User Avatar
    Gold Member

    Ding, ding, ding! The egg sitting on the lip of the flask acts like a check valve, and as the candle heats the air, it allows the expanding air to escape. Once the candle has burned enough oxygen so that the air in the flask no longer supports combustion, the flame goes out, and the air in the flask cools, reducing the air pressure in the flask. The higher atmospheric pressure outside the flask pushes the egg into the flask.
  9. Aug 10, 2007 #8
    Assume that you are inside the bottle. :rolleyes:
  10. Aug 13, 2007 #9
    Thanks everyone for your participation.
    It is amazing how often people (including myself) think that burning oxygen creates a vacuum.
    But as mgb pointed out, burning the candle produces CO2, that is why it is good to do the experiment with boiling water, as it heats the air inside and expands, then as it cools the air pressure inside the flask/bottle reduces below the outside levels. Then 'PLOP' in she goes.

    Many Happy Regards
    Simon Lee from inside the bottle.
  11. Aug 14, 2007 #10
    I think there might be some reactants that react with oxygen to produce some solid, and so they can create vacuum.
    So, I think this is not really a physics problem.

    P.S. solving this mathematically is the best way though!
  12. Aug 14, 2007 #11
    Does the candle has to be inside the bottle? If not, then I'd suggest heating the air in the bottle simply by heating the bottle. If we disregard the various adverse effects of having a red-glowing bottle in contact with an egg or our skin, placing the bottle above the candle so as to heat it to as high a temperature as possible, removing the candle, placing the egg on top of the bottle while the bottle itself and the air now trapped inside cools down, should do wonders.

    By having the candle outside the bottle, much higher temperatures can be achieved, and thus a much better vacuum is created during cooling.
  13. Aug 14, 2007 #12
    In all fairness, everyone got the physics part of the question right, though some were more hand wavy than others. The combustion part is a chemical side note.
  14. Aug 15, 2007 #13
    Thanks for the tip, I have not heard that idea before.
    However the misconception is that you create a vacuum, when it comes down more to air pressure.
    If anyone has a detailed explanation could they please attach it. I will be doing detailed lesson plans to dispell the myth in class.

    Thanks again to all who have responded.
  15. Aug 28, 2007 #14
    Any Ideas for lesson plans to dispell the misconception?
    Cheers Simon
  16. Aug 28, 2007 #15
    Do the experiment as a demonstration or practical depending on the maturity of the students. Gather some ideas from the class as to why this is happening.

    Then you bring in another 2 bottles, both with candles and eggs.

    Do the experiment simultaneously as normal, BUT, keep one of the bottles warm, and it shouldn't suck the egg in. Then ask the class to find the difference. It should be pretty obvious to them from this second demonstration.

    Make sure you experiment by yourself beforehand. Nothing cooler than stuffing up.
  17. Aug 29, 2007 #16
    Thanks great idea.
  18. Aug 29, 2007 #17


    User Avatar
    Science Advisor
    Homework Helper

    I've always wondered if condensation of water vapor from the burning process might have as much to do with the sucking as the thermal effect. Would you do that and let me know what happens?
  19. Aug 30, 2007 #18


    User Avatar
    Science Advisor
    Homework Helper

    Assuming a solid fuel with negligible volume.
    CxHy + O2 -> H2O + CO2

    You create one mole of CO2 for each mole of O2 used
    The ratio of C and H in the fuel depends on the particular hydrocarbon but in longer chains it is going to approach 1 so you use a quarter as much O2 to create H2O.
    This uses up O2 gas and creates H2O liquid so it does reduce the volume.
  20. Aug 30, 2007 #19


    User Avatar

    It's a space-time thing... right?
  21. Aug 30, 2007 #20

    Time is just an invention to sell clocks...

    And space is just a vacuum....

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook