If an inverted glass jar is put over a burning candle, resting in a shallow bowl of water, the candle?

If an inverted glass jar is put over a burning candle, resting in a shallow bowl of water, the candle
burns for a few seconds longer and then goes out. Explain what happens to the water level inside
the jar, together with the reasons for this behaviour.

  1. Mayumi
    on November 30th, -0001

    You have basically described the Bell-Jar experiment used to prove the existence of Oxygen being required for combustion and that it occupies approximately 20% by volume of the atmosphere at sea level.The water level rises because the Oxygen combines with the carbon to from CO2, and hence a partial vacuum is created inside the jar to the extent of the space occupied and the pressure exerted by the oxygen.
    Life’s Lovely! Love & Live Life!

  2. CaptainCrunch
    on November 30th, -0001

    the water level rises
    the candle uses the oxygen which creates a vacuum in the jar

  3. KoolKermit
    on November 30th, -0001

    Yup, Russ has it.

  4. Cookie Monster
    on April 1st, 2011

    I totally agree but Mayumi can u make that alittle more clearer plzz?? u see I am doing a test thing and I need to know why the water gets in the jar I am just going to write what catin crunch wrote thanxx!!

  5. paula
    on May 4th, 2011

    i need the answer for this

  6. Shekhar
    on July 2nd, 2011

    Sorry but the answers given above are incorrect. The water level in the Bell jar increases after the flame (hot gases) cool down creating a partial vacuum.
    The consumption of oxygen does not create partial vacuum As it is replaced by carbon dioxide and a little of water vapor. Carbon dioxide is practically insoluble in water. Water vapor will condense after some time and create a very partial vacuum in sufficient to explain The observations.

  7. Andy
    on September 3rd, 2011

    You may be surprised to learn that this age-old experiment has been misunderstood until quite recently. The candle actually warms the air, which expands and can be seen to bubble out under the glass. This is what causes the vacuum. The oxygen is not “used up”, it is still there attached to the carbon from the candle as carbon dioxide. This error in reasoning was discovered by schoolchildren who tried using two candles, which resulted in a greater vacuum!

  8. Dave
    on September 25th, 2011

    There is actually two reasons the water level will rise. It is best to look at a combustion equation to understand how it works (this equation is meant for methane so it’s slightly different but same principle).

    CH4 + 2 O2 → CO2 + 2 H2O

    1) The pressure exerted by the air on the water will decrease. This is because we are reducing the number of air molecules when the burning occurs. In the above equation we can see we have two molecules of O2 being converted to one molecule of CO2.

    2) We can also see that the combustion reaction produces water- also causign the water level to rise.

  9. Aunty Teressa
    on October 12th, 2011

    Me 2

  10. Ian
    on November 24th, 2011

    When the candle burns it uses the oxygen. BUT replaces it with both Carbon Dioxide and Steam. When the candle goes out the hot steam cools down until it condenses as water. At that pont there is a net drop in volume and the drop in pressure inside the jar cannot prevent the external atmosphere pushing water up into the jar. Watch the experiment carefully.

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If an inverted glass jar is put over a burning candle, resting in a shallow bowl of water, the candle?

If an inverted glass jar is put over a burning candle, resting in a shallow bowl of water, the candle
burns for a few seconds longer and then goes out. Explain what happens to the water level inside
the jar, together with the reasons for this behaviour.

  1. GodThingie
    on November 30th, -0001

    You have basically described the Bell-Jar experiment used to prove the existence of Oxygen being required for combustion and that it occupies approximately 20% by volume of the atmosphere at sea level.The water level rises because the Oxygen combines with the carbon to from CO2, and hence a partial vacuum is created inside the jar to the extent of the space occupied and the pressure exerted by the oxygen.
    Life’s Lovely! Love & Live Life!

  2. ShoeLover
    on November 30th, -0001

    The candle will consume the oxygen in the glass; since the partial pressure of the oxygen is gone, the level of the water will rise slightly.

  3. BlueButterFly
    on November 30th, -0001

    The water level will rise as the oxygen is burnt off by the candle.

  4. FantasyFootball
    on November 30th, -0001

    sounds like a homework question – suffice to say not all the atmosphere is burnable Oxygen and any that is burn’t has to be replaced (nature abhors a vacuum)

  5. Sunflower
    on November 30th, -0001

    The O2 will be consumed and will take up less space, that will allow the water level to rise in the bell jar due to the drop in pressure in relation to the atmospheric pressure. A boiled egg will be drawn into a glass milk bottle when placed at the mouth of the bottle with the candle lit in the bottle.

  6. ShinyStars
    on November 30th, -0001

    The candle burns as long as the oxygen lasts, but when the oxygen is gone, the air pressure lessens so the water level goes up a little.

    Hope that helps.

  7. EgyptianWonder
    on November 30th, -0001

    I have a friend who taught biology, chemistry, and earth sciences, and I am waiting to get the answer back from him as I type. I suggest that you can go to http://www.drdino.com and click on the “contact” link and have them respond if you are in a hurry. The candle will only burn as long as it has oxygen, and I believ that it will draw the water up into the jar. When the great flood happened (back around 4004 B.C.) the earth originally had a “hyperbaric” type of atmosphere. There was awater-ice “canopy that was around the ozone. I say that because, as you know, the sun will x-ray you the whole time you stand out in it. It has “good” rays and “bad” rays. The only thing that will keep you protected is a lead umbrella or a cloudy day. The sun, just like the x-ray machine, shoots thousands of little x-ray, beta ray, and gamma rays, into your carcass everyday! That water/ice canopy collapsed and fell to the earth and as it hit earth’s atmosphere it became condensation (a.k.a. rain) and hit the ground and began to rise and rise. So then, the question is, “What happened to the original atmosphere that was around the earth?” Since water is more “dense” than air, the atmosphere was “pushe up” and “out” into outer space. This would also tend to weight the earth down more, thus, making it heavier, and possibly pulling it out of it’s original orbit. This is proven by simply pouring water in an empty glass. What happens to the air in the glass? It is pushed up and out into the atmosphere and gives place to the water. That is also why the earth is 4 days off in it’s rotation around the earth more than likely. There was more vegetation back then, better air, no death, no war, no famine, things grew to huge proportions, and yes Virginia, there were dinosaurs! The word “dinosaur” didn’t even pop into the dictionary until 1841! Before that they were called “dragons”! Simply big lizards that, in a perfect enviroment, never stop growing. But then we have the Smithsonian Institute that was put here to try to promote evolution and cover up the archaeological finds of “giant” things from years ago, like 9′-12′ human skeletons. Check out the “Mizner Effect”.

  8. Praveena
    on July 2nd, 2011

    We understand its the oxygen gets consumed by the flame so the air pressure drops and water risies. Why ies the water level ris increase as we increase the number of candles as shown in the below video??

    How does air loose more pressure when we increase the number of canles we place in the jar??

    http://www.youtube.com/user/arvindguptatoys#p/u/14/_pkiJfogE-c

  9. udit malhotra
    on August 15th, 2011

    pagal ho gayho kya

  10. Robert Fields
    on December 1st, 2012

    A third (less significant) reason is that the heat created by the flame reduces the pressure directly above the candle creating lift and causing it to rise slightly. When the gas above the candle cools the lift is removed and the candle displaces more water causing the level to rise.

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