Investigation on how long a candle burns under a glass beaker.

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Katrina Farrant 10HA                                                                                         Chemistry                                      October 21st 2002                                                                                     Burning Candles

Investigation on how long a candle burns under a glass beaker

Aim

I am planning to investigate how long a candle burns for when put under a glass beaker. I am also aiming to see whether it is the candle or the size of the beaker that determines how long the candle burns for. I also want to find out if you can determine the volume of a gas jar, just by timing how long the candle burns for when placed underneath.

Prediction/Hypothesis

The burning of the candle is called combustion. This is the reaction of a substance with oxygen from the air. During combustion, the candle that burns is oxidised to produce oxides. Also, energy is given out in the form of heat, light and sometimes sound energy.

Combustion is a reaction that requires oxygen. Any specific volume of air will only contain a limited and fixed percentage of oxygen gas molecules.

            I predict that the larger the beaker, the larger the volume of gas inside the beaker. Therefore, the more oxygen molecules in the beaker, which then means the longer the candle will be lit for, because the reaction will stop when the oxygen level drops too low.

As combustion requires oxygen, it follows that the larger the beaker, the more oxygen will be available for the reaction, and the longer the reaction will last for. The oxygen is removed from the air during the reaction. The increase in volume of atmospheric gas will make more oxygen available for the reaction. The more oxygen that is available, the more that combustion can use.  

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A fire needs three things to keep it going; fuel, oxygen and heat. Without these, a fire will go out. The flame of a candle needs the oxygen inside of the beaker to carry on burning. The more oxygen there is, the more the candle can use. The larger the beaker, the more oxygen that it contains. So, the larger the beaker, the longer the candle will burn for.

Plan

First of all we set up our apparatus.

Equipment

Five different sized beakers  

  • 105cm cubed
  • 282cm cubed
  • 500cm cubed
  • 600cm cubed
  • 1100 cm cubed
...

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