The three candles
Discover the ‘3 Candles Experiment’ and find out which candle extinguishes first and why. This intriguing scientific exploration delves into the mechanics of combustion. Join me in this experiment to observe the fascinating interplay of physics and chemistry
What you need:
- 3 candles of different lengths
- A glass of water
- Food coloring
- A deep plate
- A large glassware
What to do?
- Glue the candles to the plate.
- Light the candles.
- Add a little food coloring to the water and pour into the plate.
- Cover the candles with a glass container.
- Look at the candles.
- You can see that after a few seconds the candles go out in order. Starting with the highest candle to the low candle.
What is happening?
In this experiment you can see several phenomena, first, the candles go out after being covered with a container. Second, you can see that they go out in order from highest to lowest. Finally, it is possible to notice that the water that was in the plate is pumped into the vessel.
Why do these phenomena occur?
Why do the candles go out:
During the combustion process, oxygen is consumed and in return water vapor and carbon dioxide gas are released. The candles go out because at a certain point the concentration of oxygen in the air drops and there is not enough of it to sustain the combustion.
Why does the tall candle go out first and the low one last:
The hot products of combustion and especially carbon dioxide rise and accumulate in the upper part of the vessel, although carbon dioxide is heavier than air, the fact that it is hot makes it lighter than air and it rises up, similar to a hot air balloon. Because of the carbon dioxide rising upwards, the oxygen at the top of the vessel is displaced and pushed down to the bottom so the top candle goes out first, as more and more carbon dioxide is formed, it fills more of the vessel and the lower candles also go out.
Why does the water rise:
Many think that because the oxygen is burned the water rises to fill its place, this reason is only responsible for a small part of the rise of the water. In fact, the reason the water rises lies in the fact that hot air expands and cold air contracts, when we place the vessel on the candles the air in the vessel heats up and expands, after the candles are extinguished the air cools and contracts, the contraction of the air creates a negative pressure (vacuum) inside the vessel and the water are drawn in.
Look at the Fire resistant balloon experiment for more science fun
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