I lit a candle in an inverted jar over water. Water is rising with number of candles. Why?
20% of Oxygen is available in the atmosphere. To prove this an experiment is performed in schools with a jar and candle. When I lit a candle in an inverted jar over water, the flame went off after few second and the water started raising inside the jar. The raise was less than 10% of jar volume. When I lit 2 candles inside the jar, the volume of water rasised inside the jar was doubled. I keep on increasing the number of candles and found that the water was proportionally raising with number of candles lit. At one stage water has raised more than 50% of the jar.
If the atmospheric oxygen is only 20 %, water should not raise in the jar more than 20% of its volume.
What may be the reason for the above result?
The water rises in the jar as it replaces the volume of oxygen being used by the candle, in order the maintain the pressure difference, so if you increase the no. of candles the vol. of O2 burned would also increase and so the level of water in jar also increases.
March 9th, 2010 at 4:06 pm
floating candles??
lol i hate chemistry so me no know 0:]
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March 9th, 2010 at 4:51 pm
The water rises in the jar as it replaces the volume of oxygen being used by the candle, in order the maintain the pressure difference, so if you increase the no. of candles the vol. of O2 burned would also increase and so the level of water in jar also increases.
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March 9th, 2010 at 5:11 pm
its because the flame used up all the oxygen and created a vaccuum and pull it down to the bottom
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March 9th, 2010 at 5:56 pm
i dunno but that happens to anything like when you jump into a bathtubbb, thats filled it may overflow,
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March 9th, 2010 at 6:34 pm
This is a fascinating experiment which I do each year with my students. According to my calculations, the water should not rise more than 12% of the total volume, as CO2 is being produced by the reaction to replace the used O2. I still, after many years, cannot determine a satisfactory reason for the unusual rise in the water level. Perhaps it is a combination of factors of heat, pressure, water vapor etc. Keep on experimenting and remember to think sideways.
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March 9th, 2010 at 6:57 pm
oxygen is being depleted by the candle and the atmosphere is becoming a vacuum
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i did that when i was in high school
March 9th, 2010 at 7:11 pm
a flame needs a certain amount of oxygen to burn. like humans need 16% to function and a fish needs 8% by the time the oxygen is reduced to the point of burn out the heat generated by the candles has heated other gases and caused them to expand and taking up more volume when the air cools it contracts creating a vacuum and pulling the water further into the jar.( the more the heat the further the expansion the more the vacuum when cooled.)
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how it works encyclopida
March 9th, 2010 at 7:22 pm
It has nothing to do with the amount of oxygen but the temperature of the air when the candles are covered by the jar. Warm air is less dense as the same volume of cold air. So as the air cools when the candles go out it creates a vacuum from the air condensing and sucking water into the jar. By using more candles it creates more hotter air thus more of a vacuum as the air cools to room temperature.
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